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c++windowsdialogacceleratormodeless

Modeless dialogs and accelerators

I want to perform some action when the user presses CTRL+S inside a modeless dialog. Accelerators would be perfect for this, except that I don't have control over the thread's message loop (think plugin), so I can't call TranslateAccelerator.

A nested message loop is not an option because the main application does a lot of processing in between calls to PeekMessage.

  • Is there some way I can 'force' the existing message loop to handle my accelerator?
  • Is there any other way besides accelerators to catch CTRL+S?

I thought about using a Window hooks on WH_GETMESSAGE, which gets called before returning from GetMessage or PeekMessage. But I'm not sure what would happen after I successfully called TranslateAcellerator, I can't let the application know I handled it. WH_MSGFILTER would require the app to implement a call to CallMsgFilter, which it doesn't from a quick glance with a debugger.

My last idea was subclassing the control which is what I'm trying to avoid. That would require some mechanism to signal the keypress event to the parent window, which I don't think is a great design. Also, if I add more controls I would have to subclass every single one.

Thanks for any hints.

Solution

  • This is a fairly infamous interop problem, it rears its ugly head also when using Winforms to implement UI in a native program. Microsoft's recommendation is a rough-and-tumble one: start your own thread to display the window so you can pump your own message loop. You'll need SetParent() to avoid Z-order problems. Scary stuff, do consider a modal dialog thrice before committing to this.