[haiku-bugs] [Haiku] #10461: SetEventMask(B_KEYBOARD_EVENTS) leads to duplicate Alt-B, Alt-V ..etc
- From: "ttcoder" <trac@xxxxxxxxxxxx>
- Date: Thu, 23 Jan 2014 12:40:15 -0000
#10461: SetEventMask(B_KEYBOARD_EVENTS) leads to duplicate Alt-B, Alt-V ..etc
--------------------------------+------------------------------
Reporter: ttcoder | Owner: axeld
Type: bug | Status: new
Priority: normal | Milestone: R1
Component: Kits/Interface Kit | Version: R1/Development
Keywords: | Blocked By:
Blocking: | Has a Patch: 0
Platform: All |
--------------------------------+------------------------------
`BView::SetEventMask(B_KEYBOARD_EVENTS)` allows a view to "snoop" on the
keyboard, i.e. makes the view receive keystrokes regardless of its being
the window's current focus view or not.
This currently works ''not by re-routing the original message (like
SetMouseEventMask() does)'', but instead by sending it normally and then
also sending a ''duplicate'' copy to the view that called
`SetEventMask()`. That in itself is not a big problem to work-around, as
each recipient (the window and the "snooping" view) is free to ignore what
does not concern it by re-implementing the concerned hooks...
Except..... in the case of Command-xyz keyboard shortcuts, due to special
treatment : they are ''not'' dispatched to both recipients -- instead they
are ''both'' handled by the ''same'' recipient, the window. They never
reach the view that called SetEventMask() (!) because
`BWindow::DispatchMessage()` processes them apart, consuming them with
`return true` here:
http://cgit.haiku-
os.org/haiku/tree/src/kits/interface/Window.cpp#n3804
and thus the target view's hooks (KeyDown(), MessageReceived()) are never
called, we never enter the `if()` here:
http://cgit.haiku-
os.org/haiku/tree/src/kits/interface/Window.cpp#n1196
Thus hitting Command-B leads to be_app.AboutRequested() being called
twice, hitting Command-V leads to the clipboard text being pasted twice
and so on for other window shortcuts... And contrarily to other keyboard
events, there is no clean possibility of fixing the misbehavior, except by
hacking/overriding BWindow::DispatchMessage(), as I had to do in my app.
Either that, or you have to forget about using
SetEventMask(B_KEYBOARD_EVENTS). Somewhat annoying.
--
Ticket URL: <https://dev.haiku-os.org/ticket/10461>
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