Mate-display-settings display glitches

[phocean]

Expected behaviour

mate-display-settings should display the screen layout properly:

Actual behaviour

The display gets corrupted once the layout is changed:

Steps to reproduce the behaviour

1. Open mate-display-settings
2. Simply move any monitor in the layout frame and observe how it gets messed.

MATE general version

1.20 and 1.22

Linux Distribution

Ubuntu Mate 18.04 and Ubuntu Mate 19.04

[lukefromdc]

I can't duplicate that on Debian Unstable and in fact have never seen that happen. Wonder what is different? If you have an Ubuntu live disk, does it happen there too? You should file a bug report with Ubuntu as this might be distro-specific. Ubuntu for instance used to patch GTK, don't know if they still do.

[willysr]

I can't reproduce this in Slackware (current) as well works fine with 1.22.1

[raveit65]

Don't use this as fix/workaround for 3-party themes!

[rave@mother ~]$ cat ~/.config/gtk-3.0/gtk.css 
/* mate-display-manager */
foo-scroll-area:selected,
foo-scroll-area:selected:focus,
foo-scroll-area:selected:backdrop {
    background-color: @theme_selected_bg_color;
}

[raveit65]

https://git.mate-desktop.org/mate-themes/commit/?h=gtk3.22&id=cab4057bd34646f6d63e86f5af7372576310f58e

[lukefromdc]

So this is theme-dependent? My UbuntuStudio_Legacy theme works fine, so does Menta in a quick test here

[raveit65]

I don't know why, but first time i noticed that with Submarine themes but not with Menta themes. I think Menta themes match it in a very general way. https://github.com/mate-desktop/mate-themes/blob/master/desktop-themes/BlueMenta/gtk-3.0/gtk-widgets.css#L37

*:selected,
*:selected:focus,
*:selected:backdrop {
    background-color: @theme_selected_bg_color;
    color: @theme_selected_fg_color;
}

Well, not all themes have this selectors and using jokers isn't a good way to do this, because using a joker like this can match more places in code and you don't know about. Best way to fix it would be to add a css or gresource file with the css function to package.

[phocean]

Yes, it seems to be theme dependent. It works with the standard Ambiant-Mate theme, and @raveit65 workaround does work.

I would have never thought that a theme could have such an impact. What's the root issue?

@raveit65 Why are you telling me not to use this workaround if it works?

[raveit65]

Why are you telling me not to use this workaround if it works?

It's a joke, the same like "Don't have sex! :) Don't hear rockn' roll etc.

[lukefromdc]

The way to ensure that globs don't screw up anything else is to fix this with a cssprovider and widget names inside mate-settings-daemon's display dialog