Gtkmm - "Gdk::Window::pointer_grab" troubles

I am programming an FPS (First Person Shooter) game using "Gtkmm" as a window manager and I would like to do the "mouse-look". Therefore, I have to "grab" the mouse pointer to redirect all the mouse motion events to my application window.

There seems to be three overloaded functions to do that job and I have chosen the simplest one for the beginning:

Gdk::GrabStatus Gdk::Window::pointer_grab(bool owner_events, Gdk::EventMask event_mask, guint32 timestamp)

I have tried to put this function to my application but I have had "bad results" so far - it doesn't do what I want it to, it behaves "differently" on "Windows" than on "Linux", etc...

So I will write down what I have done so far, but first, what is my target: "I want to have my application in a window and want to be able to do the mouse-look with a mouse even when I leave the window with the mouse pointer".

So let's get to the function parameters:

-->bool owner_events: when I set it to "true", I got events only when I was inside the window, but (worse) when I set it to "false", I didn't get any events - so I set it to true (the better option :-) )

-->Gdk::EventMask event_mask: there should be those events which I want to catch. For now, I am interested only in mouse motion events, so I put there only "Gdk::POINTER_MOTION_MASK"

-->guint32 timestamp: this I also don't understand but when I put there pure "0", the grab status was OK, thus "GRAB_SUCCESS" (when I tried to set it to 1, 2 or whatever other number, it returned "GRAB_INVALID_TIME" as a grab status) - so I set it to "0"

And now when I run it on Linux, it although grabs the pointer and when I click somewhere outside the window, it doesn't react (thus my window stays always at the top, which is what "I want"), but the problem is that, that the application doesn't catch any events 开发者_开发问答or catches it only when I am inside the window (when I set owner_events to true).

And on Windows it is yet worse: when I click somewhere outside the window, it switches me to the area where I clicked - so this is the same as "without grabbing".

Could someone tell me, what I am doing wrong, or give me a little example on using grabbing in Gtkmm?

For the event_mask, you should include Gdk::ENTER_NOTIFY_MASK and Gdk::BUTTON_RELEASE_MASK so you can ungrab the point when it either reenters the window or when the button is released.

For timestamp, either pass the GdkEvent...::time member, or Gdk::CURRENT_TIME.