I wanted to try gtk3-nocsd. According to the documentation, it is intended for non-GNOME desktops, but I wanted to try anyway if it will work under GNOME. (In case someone doesn't know, this package should force the programs that use CSDs to drop them and display all the widgets that would be normally in the title bar, in an additional "menu" bar under the title bar - title bar remains containing only the title and minimize/maximize/close buttons, as it should).
Indeed it works properly when I run a program via gtk3-nocsd command - for example gtk3-nocsd gedit (although gnome-tweaks does not behave properly when run this way and still displays CSDs - I don't know why). I can also explicitly set an environment variable GTK_CSD to 0 and then run the program.
However, I can't activate it globally in the GNOME session. According to the documentation, I should put the following statement into my ~/.xsessionrc file:
export GTK_CSD=0
However, after logging out and back in, when I check the environment variables, GTK_CSD is not set at all. I supposed that my ~/.xsessionrc is not sourced, but when I put in a similar command referring to a different, totally random environment variable, the variable is present. So ~/.xsessionrc is sourced, but GTK_CSD variable seems to be explicitly ignored/overridden by GNOME.
I also tried to explicitly add export GTK3_NOCSD_IGNORE=0 to the file. The variable is visible in the environment, but GTK_CSD still isn't, and the behaviour doesn't change.
Is it possible to activate gtk3-nocsd globally? If yes, how?
Ubuntu 20.04.
