This fixes the flash of all windows on all workspaces that one can see in the window list when returning from Expo and Scale.
Steps to reproduce:
Expected behavior: The window list should be empty on return to an empty workspace.
Actual behavior: The window list is initially populated with all windows on all workspaces, before being updated to show the windows on the current workspace.
Current status: Ready For Test.
[window-list applet] Make window icons on panel immediately reflect c…
…urrent workspace's windows on return from Expo and Scale, avoiding accidental flash of all windows.
[window-list applet] Some cleanup.