Ghosting when tiling a window moves it to the next monitor

[KMouratidis]

Describe the bug

I have a single, simple tiling setup with 2 side by side windows (just like the gnome default), 3 monitors side by side (A-B-C, same resolution and scaling), and Super+Arrow to tile left/right. Let's say I tile a Window to the right side of monitor A, and press Super+Right, then the window (correctly) moves to the left side of monitor B, however, during that transition there is a visual artifact that looks like ghosting that reaches all the way to the right of screen B.

I think the reason is that the window is first moved to the next monitor and then resized, e.g. here: https://github.com/domferr/tilingshell/blob/main/src/components/tilingsystem/tilingManager.ts#L993-L1002

I tried skipping the move_to_monitor animation like this:

...
        // move and resize the window to the current selection
        if (window.get_monitor() !== this._monitor.index) {
            Main.wm.skipNextEffect(windowActor);
        }
        window.move_to_monitor(this._monitor.index);
        window.move_resize_frame(
...

and the ghosting is gone, although so is the animation. I also tried something like:

...
        TilingShellWindowManager.easeMoveWindow({
            window,
            from: beforeRect,
            to: destRect,
            duration: 1,   // tried higher values too, e.g. 250
            monitorIndex: this._monitor.index,
        });
        // @ts-expect-error "Main.wm has the "private" function _prepareAnimationInfo"
        Main.wm._prepareAnimationInfo(
...

which also didn't cause ghosting, but the animation was weird.

Information (please complete the following):

• Tiling Shell version: 17.3
• GNOME version: 50.3