19.10 : wallpaper mess when changing screen layout

[phocean]

Hi,

In 19.10, among Caja or Marco, which is in charge of drawing the wallpaper?

Because an issue I reported a while back is getting worse : I cannot use a wallpaper and plug/unplug HDMI screen, as I would get that:

Whatever the setting is, changing the screen layout event totally mess the rendering of the background.

I used to warkaround it by enabling "display desktop icons", so that Caja took care of the rendering (it did manage it correctly, or at least it refreshed the settings somehow).

Now, it happens in both cases, so image wallpapers are just unusable. I feel Marco is doing the rendering, but I may be wrong.

I could reproduce it with several computers, including fresh installs, so I would be surprised that no one else has never noticed that.

Do you have any clue?

At least, against which component should an issue be properly reported?

[vkareh]

The background rendering is a mess and needs to be completely redone.

Currently it's a combination of mate-desktop and caja, but if you're using multiple screens at different resolutions, you need to add mate-settings-daemon, marco, and maybe even mate-panel to the mix.

There's no one single place where background rendering is happening, and that's a problem. Things are fighting each other and there are likely circular dependencies.

I don't know whether there's a bug filed specifically for this, or where, but I have been dragging this in my to do list for a few years now. It's not trivial to fix, unfortunately

[Utsuro]

I experience the exact same problem when adding an HDMI monitor and like you mentioned on github, going to the background tab of mate-appearance-properties helps but is not convenient.

As a workaround I use a script to load a background made for the extra monitor space (3840x1080 instead of 1920x1080) and use the "spanned" picture option to fit it properly when using two monitors . As I assign it to a keyboard shortcut, this is not too much of a hassle.

If you want to try it you might want to delete/comment the lines related to custom layouts as they're broken in 19.10 as well as the Plank related lines if you don't use the Plank dock.

Should you want the same background on both monitors and since you use 1920x1080 and 2560x1440 monitors, I assume you should use a 2560x1440 background with the 'zoom' picture option instead of 'spanned'.

Hope this helps.

[phocean]

Thank you for the replies @vkareh and @Utsuro
It looks really ugly, worse than I thought (I imagined a simple bug).

I will keep using plain color backgrounds then, because I want to keep things simple. This is really disappointing through, as it's a basic feature everywhere.

@vkareh any chance that the future plans with Wayland/Mir may help or will it still be unrelated in terms of architecture?

Otherwise, can't there just be a reload of the settings as a simple workaround?

EDIT : By the way, is that ok to keep tracking it in the issue mentioned in my post? I am also asking it for sponsoring stuff.

[vkareh]

I think Wayland/Mir are unrelated to this. Yes, please let's keep tracking it there, as that issue has good information in it.

[mircea]

For me this looks more like a feature request than an issue... as the wallpaper resolution does not match what screen has, this can be enlarged to fit screen and after cut to remove a part of top and/or bottom in Gimp...

[vkareh]

Part of it may be feature request, but the background rendering is a mess and does not scale properly on HiDPI, causing all sorts of weird issues. In my case, whenever I start/end a session, my background shows up briefly as 4 smaller tiled versions of the large one. Occasionally I'll get that behavior randomly throughout the session.

Then there's multiple monitor configurations, in which if you have a panel in between monitors, marco does not calculate the workarea correctly, which leads to issues in how caja positions the desktop across your screen, affecting the background placement.

It really sucks