What does the "Client-side decorations" option do?

[kiamlaluno]

In the Mousepad preferences, I noticed that the Window tab has the Client-side decorations (restart required) checkbox.

I selected that option, closed Mousepad, restarted my laptop. When I re-opened Mousepad, I haven’t noticed any difference in how its window is rendered.

What does the Client-side decorations option exactly do?

[bogdancovaciu]

@kiamlaluno

What does the Client-side decorations option exactly do?

Last definition from 2020

Client side decorations, or simply CSD, is a technology that allows apps to draw its own window decoration on Linux without involving the window manager for that . Historically, it was a role of the window manager, which is xfwm4 in case of Xfce. In GTK3, this is implemented using the GtkHeaderBar widget.

In layman terms, with it, some applications that had that thinner title bar, with only close, maximize, minimize buttons, now will have the HeaderBar version, a bit larger, with some of the GTK+ features into it, like the hamburger menu …

[maycne.sonahoz]

https://wiki.archlinux.org/title/GTK#Client-side_decorations

[kiamlaluno]

For Mousepad, the only difference I noticed is that the title bar background for the inactive windows uses a different color respect other windows, for example Thunar windows.