Windows go blank when I try to undecorate (mutter problem?)

[Amy <mathematical coffee gmail com>]

Hi all,

WIth the release of GNOME Shell 3.10, I'm trying to update my extensions to 3.8...

In particular, I have an extension that undecorates windows when they are maximized (maximus).

For various reasons one way the extension does this is to modify the '_MOTIF_WM_HINTS' of the window as opposed to setting the 'GTK_SET_HIDE_TITLEBAR_WHEN_MAXIMIZED' flag (note - the extension *does* do this by default but a couple of window themes, notably Ubuntu's Ambiance and Radiance don't seem to support this and in these cases I fall back to MOTIF_WM_HINTS).

I have noticed a bug (maybe?)::

I find that in GNOME 3.8 with any theme (e.g. Adwaita), if I go to the command line and do:

    xprop -f _MOTIF_WM_HINTS 32c -set _MOTIF_WM_HINTS '0x2, 0x0, 0x0, 0x0, 0x0'

(the above sets a window to be undecorated)

and then click on a maximized window of my choice to undecorate, the contents of that window go blank. When I unmaximize the window, the contents appear again. (Or, I can choose an unmaximized window and it undecorates, but when I maximize it the contents go blank).

In either case the window is undecorated as I expect, it's just that when I maximize it the window goes blank.

Note that this happens *even when I do not have my extension installed*, so it is not an extension problem.

**How may I go about tracking down why this happens and how to fix it?**

I asked on IRC a long time ago and someone mentioned it could be to do with frame synchronization in Mutter, and there was a particular person I was meant to ask (don't remember the name) but they were not online at the time (I'm from Australia so have trouble lurking when people are online).

Screenshot of what I mean by the window going "blank": https://www.copy.com/s/4KM3qGD3vcVm/DeepinScrot-2453.png

cheers,

Amy