fix: don't tile/move the desktop-icons window on Super+Arrow

[4mGLn]

Summary

Fixes #183 — desktop icons appear to "float"/shift when pressing Super+Left/Right/Up/Down while no application window is focused (e.g. right after clicking empty desktop space).

Why this happens

_onKeyboardMoveWin in extension.ts is the handler for both the move-window and span-window signals — i.e. it's what runs on every Super+Arrow press. Its guard bails out when there's no focused window, when the focused window has lost focus, when its wm_class is gjs, or when it's fullscreen:

if (
    !focus_window ||
    !focus_window.has_focus() ||
    (focus_window.get_wm_class() &&
        focus_window.get_wm_class() === 'gjs') ||
    focus_window.is_fullscreen()
)
    return;

But display.get_focus_window() doesn't only return normal application windows. When you click on empty desktop space, GNOME can hand keyboard focus to the desktop-icons window (Nautilus desktop / Desktop Icons NG). That's a real Meta.Window, just one with windowType === Meta.WindowType.DESKTOP instead of NORMAL. None of the existing guard conditions filter it out, so _onKeyboardMoveWin proceeds to tile/resize that window through monitorTilingManager.onKeyboardMoveWindow(...). Resizing the desktop-icons window's frame is exactly what makes the icons appear to shift/float — Tiling Shell ends up unintentionally treating the desktop background as a tileable window.

Notably, _onKeyboardUntileWindow already guards against this same case with a focus_window.windowType !== Meta.WindowType.NORMAL check — it was just missing from _onKeyboardMoveWin.

Fix

Add the same windowType !== Meta.WindowType.NORMAL guard (already used elsewhere in this file) to _onKeyboardMoveWin, so Super+Arrow is a no-op whenever the "focused window" isn't a real application window.

Test plan

• npm run build succeeds
• Built extension installed locally on GNOME Shell 46 (Ubuntu 24.04), Tiling Shell v17.3
• Verified after full logout/login: click empty desktop space, hold Super+Arrow — desktop icons no longer move