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c++winapidrop-down-menucomboboxdisabled-control

Disabling a ComboBox item in Win32 API

I would like to disable an item in a combobox in my Win32 application (C++). I'm not quite sure how to do this. I'm trying to achieve something that looks like this:

Disabled combobox item

Notice how CollectionItem2 and 3 are greyed-out.

Any help would be very much appreciated!

Solution

  • If you truly need a combobox for this, then (as @IInspectable said) you'll need to do a custom drawn control. Basically, you'll have to store some information saying which items are disabled/grayed, and draw the items appropriately based on whether they're enabled or not.

    There may be a somewhat easier way though. This is normally done with a Split Button. This is button with the BS_SPLITBUTTON style set. When the drop-down part of the button is clicked, it sends a BCN_DROPDOWN notification.

    You normally respond to that by displaying a menu, typically using TrackPopupMenu to display it immediately below the button (or immediately to its right, if you prefer). This is a normal menu, so it can have items enabled, disabled, grayed, have check boxes, etc., as you see fit.

    If you're using MFC, it has a CSplitButton class that wraps the Split Button, simplifying the code a little bit--you can pass an identifier of a menu and sub-menu when you create the CSplitButton object, and it handles things from there.

    A sample result probably looks pretty familiar:

    enter image description here

    Note: MFC also has a CMfcMenuButton class. This has roughly similar functionality, but is somewhat clumsier to use. If memory serves, it is compatible with older versions of Windows (but the split button goes back to Vista, so it's fine unless you really need to support XP).