Question

I have a CDialog that is calling DoModal(), the dialog is opened, everything else is disabled, but for some reason I have only the keyboard capture and not the mouse.

The mouse capture is still on the last item it was on.

If I call setfocus before the DoModal, it doesn’t work, but if I do setCapture before the DoModal it works.

Can anyone explain it to me?

What is the problem? I want to understand why I need to call to setCapture or releaseCapture before the DoModal (btw- releaseCapture works as well…)

Answer 1

There is no such thing as ‘keyboard capture’. There is just keyboard focus.

A window that has the keyboard focus is the one that receives the keyboard related messages.
Mouse messages are normally sent to the window just beneath the mouse cursor, without regard to the focus. That is unless the mouse is “captured”, in this case mouse messages are sent to the windows that has captured the mouse, no matter where the mouse cursor is.

That said, do you really need to capture the mouse? Actually that is rarely necessary. And it should be done only as a consequence to a user action, never on your own.

PS. Due to security concerns, in Windows there are actually two different kinds of mouse captures:

• Local captures: mouse messages are sent to the capturing window, only if the mouse is over a window that belongs to the same application.
• Global capture: mouse messages are sent to the capturing window, no matter where the mouse cursor is.

The SetCapture function creates a global capture only if it is called while processing a WM_?BUTTON_DOWN message.