GNOME Bugzilla – Bug 736822
_NET_FRAME_EXTENTS hint in openbox
Last modified: 2018-04-15 00:09:10 UTC
Hi, Opensnap, an application which provides aero snap feature in openbox, doesn't work with Evince and other applications which use CSD. It seems like reason for this problem is in fact that those applications don't send information about correct titlebar size. Please see the comment from Opensnap developer: https://github.com/lawl/opensnap/issues/19
there is no way for applications to send information about the correct titlebar size. _NET_FRAME_EXTENTS is a property that gets set by the window manager
Why do you need to know about the titlebar in the first place ? I could understand wanting to know about shadows and invisible borders. That information is actually available, in the _GTK_FRAME_EXTENTS property.
Thanks for your answer but it's obvious that _NET_FRAME_EXTENTS is different for CSD applications compared to others. To quote Opensnap developer: "Opensnap needs to know the size of the titlebar, right now it gets this from the EWMH hint _NET_FRAME_EXTENTS. With a regular window this looks like this: _NET_FRAME_EXTENTS(CARDINAL) = 0, 0, 18, 0 With a CSD window it looks like this: _NET_FRAME_EXTENTS(CARDINAL) = 2, 2, 2, 2" That's why I thought there might be problem somewhere with Gtk. If not, then what else? Openbox?
Yes, it is different - it is set by the window manager, and a csd window looks different to a wm than a traditional window. _NET_FRAME_EXTENTS is not documented as 'the third number is the titlebar height' - it is simply the dimensions of the frame that the wm puts around the window. For csd windows, that is rather small. My question from comment 2 still stands.
"Why do you need to know about the titlebar in the first place ?" Well I don't, it's the application called Opensnap that use it for doing its work, or precisely to maximize window when its titlebar is dragged to the top, or maximize it vertically to the half of the screen when dragged to left or right screen border. Openbox does not have this functionality by default, so I wanted to use this application. I've understood your explanation. _NET_FRAME_EXTENTS hint is correct, there is no problem with Gtk, and Openbox doesn't show titlebar size because it doesn't draw titlebar at all. And there is no way for window manager to know that titlebar is moved to the screen edge, because for these type of applications Gtk is responsible for showing window decoration.
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