wrapper program to reparent app window w/o window frames

Question

I'm using the Cinnamon desktop environment (on Debian Sid), whose window manager has no option to, let's say so, undecorate an application window.

As I see that a number of programs manage to tell the above window manager that they will provide frames and whatsnot on their own (e.g., google chrome), I wonder if it exists, or can be written, a wrapper to be called like this

$ noframes mupdf my16:9slides.pdf

that starts, tell the window manager not to worry about frames etc, starts my application and reparents it.

The (maybe marginal) benefit is that the window aspect ratio, in my example, will be more approximately equal to 16:9 and the window will fit almost exactly the available space when using the zoom to 1/4 screen feature.

PS: from my .twmrc

NoTitle {"mupdf" ...}

Answer 1

May be you can disable/enable you title bar with this code:

#!/usr/bin/python2
from gtk.gdk import *

w=window_foreign_new((get_default_root_window().property_get("_NET_ACTIVE_WINDOW")[2][0])

if w.get_decorations() == 0 :
    w.set_decorations(DECOR_ALL)
else:
    w.set_decorations(0)

window_process_all_updates()

It comes from this gist. That is based on this post about removing decoration on specific WMs.
As it is mentioned in the article, you can create a shortcut to remove decoration of the windows you are interested in.

In the Cinnamon Keyboard Shorcuts, bind a sequence (I use Super+U) to that script, providing it is executable and in the your PATH. On an active windows, hit the sequence and it will remove the decoration. Hit it again and it will come back.

Answer 2

I have no installation to test this, but it seems there might be a "Cinnamon Maximus" extension that removes decorations from fullscreen windows, if your application can go fullscreen, albeit with borders.

Aternatively, you might try something radical like setting the window's overrideredirect flag. This asks the window manager not to manage the window. Then re-parenting the window to the root window. Beware, you may not be able to get out of this fullscreen mode, so make sure you can exit the application somehow.

For example, run xlogo, get the root window id, and use xdotool to change the xlogo setting:

$ xlogo &
$ xwininfo -root | grep id:
xwininfo: Window id: 0xc1 (the root window) (has no name)
$ xdotool search xlogo  set_window --overrideredirect 1  windowreparent 0xc1