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7 MENUS 7.1 INTRODUCTION If you have been working on the Amiga you have probably used menus a lot. They are flexible tools which are easy to access and are not complicated to set up. In this chapter we will look at how you can create your own menus, how to use all the special features offered by Intuition, and how the communication between the user and the menus is executed. 7.2 MENU DESIGN You can connect a "menu strip" to every window, and when the user presses down the right mouse button, the active window's menu strip is shown at the top of the display. An example of a "menu strip": Project Block Windows Search The user can now move the pointer to one of the menu headings, while still holding the right mouse button pressed, and that menu's "item box" is displayed. An example of a "item box": PROJECT Block Windows Search |----------| | Open | | Save | | Save as | | Print | | Info | | Quit | |----------| The user can now choose the "menu item" he/she wants. The user does it by moving the pointer to the desired menu item, and releases the right mouse button. If the user wants he/she can pick several menu items at the same "menu action" by holding down the right mouse button as normal, but click with the left mouse button on each menu item the user wants to select. The user can also "drag" (holding both mouse buttons down) over several menu items if he/she wants to select all of them. You can connect a separate menu to an item if you want. That menu is usually referred as "submenu", and it consists of one or more "subitems". An Example of "subitems": (Note that the subitem box overlap the item box!) Project Block Windows Search |----------| | Open | | Save | | Save a-------------- | PRINT | to printer | | Info | to a file | | Quit -------------- |----------| 7.3 HOW TO ACCESS MENUS FROM THE KEYBOARD If you want you can allow the user to select certain menu items from the keyboard. This is very handy if it is a command the user will often use, and you want to provide him/her with a shortcut. The user can access the menu item by pressing the right "Amiga key" + another key. For example, if the user should be able to access the menu item "Open" from the keyboard by pressing the "Amiga key" + "O", Intuition will automatically add the sign "[A] O" after the item's name: PROJECT Block Windows Search |------------| | Open [A] O | | Save | | Save as | | Print | | Info | | Quit | |------------| Your program will not notice any difference between a normal menu access, and a shortcut. Remember to give enough space on the right side of the item box, so the Amiga character + sign will fit. If the item box was before 100 pixels wide you can set the width to 100 + COMMWIDTH, and everything will fit in nicely. (COMMWIDTH is a constant declared in the intuition.h file.) If the window is connected to a low-resolution screen, use the constant LOWCOMMWIDTH instead. 7.4 MENU ITEMS There exist two different types of menu items: - Action items - Attribute items Action items can be selected over and over again, and every time they are selected they will send your program a message. Attribute items on the other hand can only be selected once, and once they have been selected they need to be deselected before they can be selected again. The only way to deselect an Attribute item is to mutual exclude them (explained later in this chapter). When an attribute item is selected Intuition will put a small checkmark, [v], before the item's name. If you want to use your own designed checkmark instead of the default one, you set the CheckMark pointer in your NewWindow structure to point to an Image structure which you have declared and initialized as desired. If you use any attribute item in your menu you need to leave enough space at the left side of the box for the checkmark. If you use the default checkmark you can move the text in the menu CHECKWIDTH amount of pixels to the right. (CHECKWIDTH is a constant declared in the intuition.h file.) If the window is connected to a low-resolution screen (320 pixels wide), you should use the constant LOWCHECKWIDTH instead of CHECKWIDTH. 7.5 MUTUAL EXCLUDE This special and very useful function applies only on attribute items. The idea with mutual exclude is that when the user selects a certain item, some other attribute items are deselected automatically. For example, you are writing a wordprocessor and the user should be able to print the text as normal (plain) or with some special style (Bold, Underline or Italic). The user would then only be allowed to select Plain or one or more of the other styles (Bold and underlined for example). If the user selects Plain, all other styles should be deselected (mutual excluded). If the user on the other hand selects Bold, Underline or Italic the Plain item should be deselected. Mutual exclude works like this: 1. If the flag CHECKIT (see the MenuItem structure) is not set, the item is not an attribute item, it is an action item, and mutual exclude will have no effect on this item. 2. If the flag CHECKIT is set, the item is an attribute item, and Intuition will make sure that the CHECKED flag is not set. If it is, Intuition will automatically remove it, and the item is unselected. Every item has a MutualExclude field in which you can specify which items should be deselected when this item is activated. The first bit in the field refers to the first item in the item list, the second bit to the second item and so on. In our previous example we would set the Plain item's MutualExclude field to 0xFFFFFFFE (0xFFFFFFFE is equal to 11111111111111111111111111111110). This would mutual exclude all items except the first one. (Plain is the first item in the list, and should of course not be mutual excluded.) The other items (Bold, Underline and Italic) should have their field set to 0x00000001 (0x00000001 is equal to 00000000000000000000000000000001). This would only mutual exclude the first item (the Plain item). 7.6 OPEN A MENU If you want to attach a menu strip to a window you need to: 1. Declare and initialize one or more Menu structures. The Menu structures should be linked together, and each Menu structure has its own list of items. Each Menu structure represent one "menu heading" 2. Declare and initialize one or more MenuItem structures which are connected to the Menu structures. Each MenuItem structure represent one item. You can connect a list of "subitems" to an Item structure if you want. (Subitems use the same data structure as normal items.) 3. Call the function SetMenuStrip(). Important, before you close the window, or change the "menu strip" you must disconnect the menu from the window. You do it by calling the function ClearMenuStrip(). 7.6.1 INITIALIZE A MENU STRUCTURE The Menu structure look like this: struct Menu { struct Menu *NextMenu; SHORT LeftEdge, TopEdge, Width, Height; USHORT Flags; BYTE *MenuName; struct MenuItem *FirstItem; SHORT JazzX, JazzY, BeatX, BeatY; }; NextMenu: Pointer to the next Menu structure in the menu strip list. The last Menu structure in the list must have the NextMenu set to NULL. LeftEdge: X position of the menu. TopEdge: Y position of the menu. For the moment this field is unused since all menus are positioned at the top of the display. Set it to 0. Width: The width of the menu. Height: The height of the menu. For the moment this field is unused since all menus are as high as the height of the title bar of the screen. Set it to 0. Flags: There exist only two different flags for the moment: MENUENABLED: If this flag is set the menu is enabled, and the user can select items from it. If it is not set, the menu is ghosted and the user can not select any items from it. If you want the menu to be enabled when you submit it to Intuition you should set this flag. You can later change the status by calling the functions OnMenu() and OffMenu(). MIDRAWN: This flag is set by Intuition when this menu is displayed to the user. MenuName: Pointer to a NULL-terminated string. The text will appear in the menu box at the top of the screen. FirstItem: Pointer to the first MenuItem in the item list. These funny-named variables are for internal use only: JazzX, JazzY, BeatX, BeatY: Used by Intuition. Set to 0. Here is an example of how to declare and initialize a Menu structure: struct Menu my_menu= { NULL, /* NextMenu, no other menu structures */ /* connected. */ 0, /* LeftEdge, 0 pixels to the right. */ 0, /* TopEdge, for the moment ignored by */ /* Intuition. Set to 0. */ 60, /* Width, 60 pixels wide. */ 0, /* Height, for the moment ignored by */ /* Intuition. Set to 0. */ MENUENABLED, /* Flags, this menu should be enabled. */ "Project", /* MenuName, the title of the menu. */ &first_item, /* FirstItem, pointer to the first item */ /* in the list. */ 0, 0, 0, 0 /* JazzX, JazzY, BeatX, BeatY */ }; 7.6.2 INITIALIZE A MENUITEM STRUCTURE The MenuItem structure look like this: struct MenuItem { struct MenuItem *NextItem; SHORT LeftEdge, TopEdge, Width, Height; USHORT Flags; LONG MutualExclude; APTR ItemFill; APTR SelectFill; BYTE Command; struct MenuItem *SubItem; USHORT NextSelect; }; NextItem: Pointer to the next MenuItem structure in the item list. The last item should have its NextItem field set to NULL. LeftEdge: X position of the item's select box relative to the LeftEdge of the Menu structure. TopEdge: Y position of the item's select box relative to the topmost position allowed by intuition. The topmost position is automatically calculated by Intuition which examines the font size, how many items above etc. Set TopEdge to 0 in order to select the topmost position. Width: The width of the item's select box. Height: The height of the item's select box. Flags: Here are the flags you and Intuition can use: CHECKIT: Set this flag if you want the item to be an attribute item, else it will be an action item. If you set this flag Intuition will put the small checkmark in front of the itmetext when this item is selected, so make sure there is enough space for it. CHECKED: If the item is an attribute item (the CHECKIT flag is set), this flag is set by Intuition when the item is selected by the user. The flag is also automatically removed by Intuition when this item is mutual excluded. You can set this flag yourself before you submit the menu strip to Intuition, if you want the item to be initially selected. HIGHITEM: The item will be highlighted, and this flag set, when the user moves the pointer over the item's select box. You need to set one of the following four flags which will tell Intuition what kind of highlighting you want: HIGHCOMP: Complement the colours of all the pixels in the item's select box. HIGHBOX: Draw a box around the item's select box. HIGHIMAGE: Display an alternative Image or Text. HIGHNONE: No highlighting. ITEMENABLED: If this flag is set the item is enabled, and the user can select it. If this flag is not set, the item is ghosted and the user can not select it. If you want the item to be enabled when you submit it to Intuition you should set this flag. You can later change the status by calling the functions OnMenu() and OffMenu(). ITEMTEXT: If the item is rendered with text you should set this flag. Intuition will then expect ItemFill and SelectFill to point to IntuiText structures. If this flag is not set the item will be rendered with an image, and Intuition will expect ItemFill and SelectFill to point to Image structures. COMMSEQ: If the item also should be accessible from the keyboard you need to set this flag. Remember to tell Intuition which key should be pressed together with the "Amiga key" in order to select the item. You do it by giving the variable Command the desired character. ISDRAWN: This flag is set by Intuition when this item's subitems are displayed, and cleared when not. MutualExclude: This variable will tell Intuition which attribute items should be mutual excluded (deselected when this item is selected). The first bit refers to the first item in the active list (item list or subitem list), the second bit refers to the second item and so on. For example: The number 0x0000000B (hexadecimal) is equal to 00000000000000000000000000001011 (binary), and Intuition would therefore try to mutual exclude the first, the second and the fourth item. ItemFill: Pointer to an Image structure (the ITEMTEXT flag not set) or to an IntuiText structure (the ITEMTEXT flag set), which will be used by Intuition to render this item. SelectFill: Pointer to an Image structure (the ITEMTEXT flag not set) or to an IntuiText structure (the ITEMTEXT flag set), which will render this item when it is highlighted. (This field is only used if the flag HIGHIMAGE is set.) Command: If the user should be able to access this item from the keyboard, you need to tell Intuition which key should be used. This field should therefore contain the desired character. (Remember to set the flag COMMSEQ in the Flags field.) SubItem: Pointer to a subitem list if there exist on, else NULL. If this item is already a subitem, this field is ignored by Intuition. (Remember, the subitem list consists of a linked list of MenuItem structures.) NextSelect: This field is set by Intuition and will contain a special number if more items after this one was selected at the same menu event, else it will contain MENUNULL. (This will be discussed later in the chapter.) Set it to MENUNULL. Here is an example of how to declare and initialize a MenuItem structure: struct MenuItem my_first_item= { &my_second_item, /* NextItem, pointer to the next item */ /* in the list. */ 0, /* LeftEdge, 0 pixels to right. */ 0, /* TopEdge, the topmost position. */ 150, /* Width, 150 pixels wide. */ 10, /* Height, 10 lines high. */ CHECKIT| /* Flags, an attribute item. */ CHECKED| /* should initially be selected. */ COMMSEQ| /* accessible from the keyboard. */ HIGHCOMP| /* complement the colours when */ ITEMENABLED, /* highlighted. The item should */ /* be enabled. Not ghosted. */ 0x00000037, /* MutualExclude, deselect if possible */ /* item: 1, 2, 3, 5 and 6. */ &my_image /* ItemFill, pointer to an Image */ /* structure used to render the item. */ /* Since the flag ITEMTEXT was not set, */ /* Intuition will assume that this is a */ /* pointer to an Image structure, and */ /* not a pointer to an IntuiText */ /* structure. */ NULL, /* SelectFill, NULL since we complement */ /* the colours instead of displaying an */ /* alternative image. */ 'O', /* Command, the character which should */ /* be pressed together with the "Amiga */ /* key" in order to execute the */ /* shortcut. */ NULL, /* SubItem, this item has no subitems */ /* connected to it. */ MENUNULL /* NextSelect, set later by Intuition. */ }; 7.6.3 HOW TO SUBMIT AND REMOVE A MENU STRIP TO/FROM A WINDOW Once you have declared and initialized the necessary Menu and MenuItem structures and linked them together you only need to call the function SetMenuStrip(), and the menu strip is connected to your window. Remember that you need to first open the window, before you can submit a menu strip to the window. If you have a pointer to an already opened window, my_window, and a pointer to the first Menu structure in your list, my_first_menu, you attach the menu strip like this: SetMenuStrip( my_window, my_first_menu ); If you want to change a menu strip which is already attached to a window you first need to remove it. You do it by calling the function ClearMenuStrip(). You can then change what ever you want to change, and attach it once again. To remove a menu strip from a window, you only need a pointer to that window, eg my_window, and then call the function ClearMenuStrip() like this: ClearMenuStrip( my_window ); If a menu strip is connected to a window, and you want to close that window, you should first remove the menu. If your program does not remove the menu strip before it closes the window, there is a risk that the user has activated the menu, and you would end up with a nice system crash. So, to be on the safe side, always call the function ClearMenuStrip() before you close a window which has a menu strip connected to it. 7.7 SPECIAL IDCMP FLAGS There exist two special IDCMP flags which are close related to menus. They are MENUPICK and MENUVERIFY. The IDCMP flag MENUPICK tells your program that the user has picked zero or more items from a menu. MENUVERIFY allows your program to finish off something before the menu is displayed, and you can even abort the whole menu operation if you want. 7.7.1 MENUPICK If you want your program to receive a message every time the user has picked zero or more items/subitems from the menu, you need to set the flag MENUPICK in the IDCMPFlags field in your NewWindow structure. You can then handle this message as normal IDCMP messages. (See chapter 8 IDCMP for more information about IDCMP messages.) Once you receive a MENUPICK message you need to check if any items were selected. The Code field of the IntuiMessage structure will contain a special code number ("Menu Number") which we can examine in order to see which item was selected. The menu number is equal to MENUNULL if no item was selected. Use the function ItemAddress() with a pointer to the menu strip and the menu number as parameters, and it will return the address of the selected item. The problem which will arise is that the user can select several items during one single menu operation, and your program needs to check them all. There is however an easy solution for this problem. If an item was selected, we can examine the NextSelect field of that item's structure, and that number is either MENUNULL (no more items selected), or another special menu number. (If it was not equal to MENUNULL you should again call the function ItemAddress() so you get a pointer to the second item's structure, and you should then examine the NextSelect field of that structure and so on...). Here is a fragment of a program which handles MENUPICK event: if( class == MENUPICK ) { /* The user has released the right mouse button. */ /* The variable menu_number is initialized with the code */ /* value: */ menu_number = code; /* As long as menu_number is not equal to MENUNULL we */ /* stay in the while loop: */ while( menu_number != MENUNULL ) { /* Get the address of the item: */ item_address = ItemAddress( &first_menu, menu_number ); /* Process this item... */ /* Get the following item's menu number: */ menu_number = item_address->NextSelect; } /* All items which were selected has been processed! */ } If you have a menu number you can use Intuitions three macros to check which menu/item/subitem was selected. They all return 0, if it was the first menu/item/subitem in the list, 1 if it was the second and so on. MENUNUM( menu_number ); Is equal to 0 if the item was selected from the first menu, 1 if it was from the second and so on. It is equal to NOMENU if the user did not select any item from the menus. ITEMNUM( menu_number ); Is equal to 0 if the firs item was selected in this item list, 1 if it was the second and so on. It is equal to NOITEM if the user did not select any item. SUBNUM( menu_number ); Is equal to 0 if it the firs subitem was selected in this subitem list, 1 if it was the second and so on. It is equal to NOSUB if the user did not select any subitem. 7.7.2 MENUVERIFY The MENUVERIFY message tells your program that the user has pressed the right mouse button, and a menu will be activated. However, the menu strip will first be activated when you program has replied, and you can therefore, thanks to this warning, wait with the menu event for a while, or even stop it totally, if necessary. If you want your program to receive a message every time the a menu will be activated you need to set the flag MENUVERIFY in the IDCMPFlags field in your NewWindow structure. The MENUVERIFY flag acts like the REQVERIFY flag for requesters. Here is an example on how your program should handle this verification message, and how you can cancel a menu operation: /* Wait until we receive one or more messages: */ Wait( 1 << my_window->UserPort->mp_SigBit ); /* As long as we can collect messages successfully, we will */ /* stay in this while loop: */ while(my_message = GetMsg( my_window->UserPort )); { /* After we have collected the message we can read it, */ /* and save any important values which we maybe want to */ /* check later: */ class = my_message->Class; code = my_message->Code; /* Before we reply we need to see if we have received a */ /* MENUVERIFY message: */ if( class == MENUVERIFY ) { /* Yes, we have received a MENUVERIFY message! */ /* The user wants to activate a menu, but the problem */ /* is that we do not know if it is our window's menu */ /* that will be activated, or some other window's menu. */ /* We can however check it by examining the Code field */ /* of the message. If it is equal to MENUWAITING, it */ /* means that it is not your window's menu that will be */ /* activated, but if Code is equal to MENUHOT it means */ /* it is is your window's menu that will be activated! */ if( code == MENUWAITING ) { /* It is not your window's menu that will be activated! */ /* Your program can take a pause if necessary. You */ /* maybe want to finish of with some drawings, so */ /* your program does not trash any menus. This is */ /* especially important if you are using the low- */ /* level graphics routines since they do not bother */ /* about, menus etc, and will draw over and destroy */ /* anything in their way. */ /* Once the program is ready it should reply the */ /* message, and the menu will be activated. */ } else if( code == MENUHOT ) { /* It is your window's menu that will be activated! */ /* You can now take a pause and finish of with */ /* something before you let Intuition activate the */ /* menu, or you can even stop the whole menu */ /* operation if necessary. If you are writing a */ /* paint program you maybe only want the user to be */ /* able to activate the menu if the pointer is at */ /* the top of the display. That would mean that the */ /* user can draw with the right mouse button, and */ /* when the user wants to make a menu choice, he/ */ /* she simply moves the pointer to the top of the */ /* display, and then presses the right mouse button. */ /* We will now check if the pointer is somewhere at */ /* the top of the display: */ if( my_window->MouseY < 10) { /* The Y coordinate of the pointer is at least */ /* less than 10 lines below the TopEdge of the */ /* window. */ /* The menu operation should continue as soon */ /* as possible! */ } else { /* The pointer is below the Title bar of the */ /* window! Cancel the whole menu operation! */ /* To cancel a menu operation you need to change */ /* the Code field to MENUCANCEL. IMPORTANT! Do not */ /* change the code variable since it is just a */ /* copy of the real Code value. What we need to do */ /* is to change the real value, and that is still */ /* OK since we have not replied yet. */ my_message->Code=MENUCANCEL; } } } /* After we have read the message we reply as fast as */ /* possible: REMEMBER! Do never try to read or change a */ /* message after you have replied! Some other process is */ /* maybe using it. */ ReplyMsg( my_message ); If you set the RMBTRAP flag in your NewWindow's Flags field you tell Intuition that you do not want to use any menus at all for this window. Your program could then use the right mouse button for something else. (See chapter 8 IDCMP for more information about RMBTRAP.) 7.8 MENU NUMBERS Here is a description of how the "menu numbers" actually work. (This can change later so do not calculate anything yourself, let Intuition's macros do it instead.) The menu number is a 16-bit variable, where the first five bits are used for the menus, the following six bits are used for the items, and the last five bits are used for the subitems: c c c c c b b b b b b a a a a a | | | | | > Menu | > Item > SubItem This means the Intuition can "only" handle up to 31 Menus, each with up to 63 Items, where each item can have up to 31 SubItems. I do not think this will be any restrictions for your program. If a field is equal to 0 it means the first menu/item/subitem, if it is equal to 1 it means the second and so on. If all bits are on it means that no menu/item/subitem was selected. See following example: The menu number 0xF803 means: No SubItem, the first item, from the fourth menu. 0xF803 (h) = 1111 1000 0000 0011 (b) Menu number 11111 000000 00011 (b) | | | | | > 00011 = 3 = fourth Menu | > 000000 = 0 = first Item > 11111 = 31 = NOSUB To calculate this you should use Intuition's macros: MENUNUM( 0xF803 ) == 3 the fourth menu. ITEMNUM( 0xF803 ) == 0 the first item. SUBNUM( 0xF803 ) == 31 (NOSUB). It sometimes happens that you want to go the other way, and calculate your own menu number. You should then use the macros SHIFTMENU, SHIFTITEM and SHIFTSUB which does the opposite of MENUNUM etc. If you are going to use the functions OnMenu() and OffMenu() (explained later), you need to send a menu number as one of the parameters. If you for example want to "ghost" the second item in the third menu, you calculate the menu number like this: menu_number = SHIFTMENU(2) + SHIFTITEM(1) + SHIFTSUB(NOSUB); [third menu] [second item] [no subitem] 7.9 FUNCTIONS Here are some commonly used function which affects menus: SetMenuStrip() This function connects a menu strip to a window. Remember that the window must have been opened before you may connect a menu strip to that window. Synopsis: SetMenuStrip( my_window, my_menu ); my_window: (struct Window *) Pointer to the window which the menu strip should be connected to. my_menu: (struct Menu *) Pointer to the first Menu structure in the menu strip. ClearMenuStrip() This function removes a menu strip from a window. Remember to always remove the menu strip before you close the window, or changes the menu strip. Synopsis: ClearMenuStrip( my_window ); my_window: (struct Window *) Pointer to the window which menu strip should be removed. ItemAddress() This function returns a pointer to the Menu or Item structure which is specified by the menu number. Synopsis: ItemAddress( my_menu, menu_number ); my_menu: (struct Menu *) Pointer to the first Menu structure in the menu strip. menu_number: (USHORT) This menu number specifies a subitem/ item/menu. OffMenu() This function can disable a subitem, an item or even a whole menu. The image or text of the disabled items etc will be "ghosted", and the user can not select them. Synopsis: OffMenu( my_window, menu_number ); my_window: (struct Window *) Pointer to the window which the menu strip is connected to. menu_number: (USHORT) This menu number specifies what should be disabled. Use the macros SHIFTMENU, SHIFTITEM and SHIFTSUB to calculate the correct menu number. If you just specify a menu, all items to that menu will be disabled. If you specify a menu and an item, that item will be disabled, and so all subitems connected to it if there are any. OnMenu() This function can enable a subitem, an item or even a whole menu. The image or text of the enabled items etc, will become normal (not "ghosted") and the user can now select them. Synopsis: OnMenu( my_window, menu_number ); my_window: (struct Window *) Pointer to the window which the menu strip is connected to. menu_number: (USHORT) This menu number specifies what should be enabled. Use the macros SHIFTMENU, SHIFTITEM and SHIFTSUB to calculate the correct menu number. If you just specify a menu, all items to that menu will be enabled. If you specify a menu and an item, that item will be enabled, so all subitem connected to it if there are any. 7.10 MACROS Here are some commonly used macros: These three macros takes a "menu number" as the only parameter, and examines it. These are very handy if you have received a menu number, and you want to check which menu and which item was selected etc: MENUNUM( menu_number ); Is equal to 0 if the menu number specifies the first menu, 1 if it specifies the second, and so on. It is equal to NOMENU if it does not specify any menus at all. ITEMNUM( menu_number ); Is equal to 0 if the menu number specifies the first item, 1 if it specifies the second, and so on. It is equal to NOITEM if it does not specify any items at all. SUBNUM( menu_number ); Is equal to 0 if the menu number specifies the first subitem, 1 if it specifies the second, and so on. It is equal to NOSUB if it does not specify any subitems at all. These three macros does the opposite of the first three. With help of these macros you can make your own menu number just by specifying which menu, item and subitem you want. SHIFTMENU( menu ); Is equal to a menu number which specifies this menu. ("menu" is a value between 0 and 30, or NOMENU if no menu should be specified.) SHIFTITEM( item ); Is equal to a menu number which specifies this item. ("item" is a value between 0 and 62, or NOITEM if no item should be specified.) SHIFTSUB( sub ); Is equal to a menu number which specifies this subitem. ("sub" is a value between 0 and 30, or NOSUB if no subitem should be specified.) 7.11 EXAMPLES Example 1 This program opens a normal window to which we connect a menu strip. The menu consists of four items: Plain, Bold, Underlined and Italic. The user can select either Plain or a combination of the other styles. (If the user selects Plain all other modes will be mutual excluded, but if the user on the other hand selects Bold, Underlined or Italic, only the Plain option will be mutual excluded. This example also shows how a program should handle the IDCMP flags, and how to collect several messages from one single menu event. Example 2 This example is very similar to Example 1, but we have this time put the edit styles in a subitem box which is connected to the one and only item box called "Style". Example 3 This example is very similar to Example 2, but the user can this time also access the subitems from the keyboard. For example, to select Bold the user only needs to press the right Amiga key [A] together with the "B" key. Example 4 This program opens a normal window to which we connect a menu strip. The menu consists of two items: Readmode and Editmode. The readmode item is selected and ghosted, and when the user selects the editmode item, it will become disabled (ghosted) while the readmode item will be enabled (not ghosted). This means that if the program is in "readmode", the user should only be able to chose the "editmode", and v.v. The purpose with this program is to show how you can use the OnMenu and OffMenu functions in order to make an "user-friendly interface". Example 5 Exactly as Example 1 except that we have changed Intuition's checkmark to our own customized "arrow". Example 6 This program opens a normal window to which we connect a menu strip. The menu consists of six small dices which are all action items. This example shows how you can use Images inside a menu. Example 7 This program opens a normal window to which we connect a menu strip. The menu consists of one small action item with two images. Example 8 Same as Example 1 except that we this time will verify any menu operations. If the user tries to activate this program's menu we check if the position of the pointer is somewhere at the top of the window (less than 10 lines down). In that case the menu operation will continue as normal, otherwise we cancel the menu operation.