Memory leak when switching window focus

When switching window focus, the system seems to lose 4KB of memory.

Steps to reproduce:

1. Open taskmgr on the perf tab
2. click in and out of any window, either from a window to the desktop or another window
3. observe phys mem->available decreasing

Reproduced on this, but I am not aware of any guilty commit.
https://github.com/reactos/reactos/commit/e636b14d7ec29c4ec9c471a39ade4181f97d845d

UPDATES:

Certainly related to what's on the desktop. The leak gets worse the more files there are on the desktop. Removing all files from the desktop completely eliminates the leak.