[app_server] deadlock while trying to close windows

[diver]

Tested with hrev28302 in VirtualBox.

Steps to reproduce:

*Boot Haiku

*Select desktop

*Press alt+f to launch find window of tracker

*Hit return and wait until it finds all possible objects (about 3880)

*Press Alt+a to select all

*Hit return and wait until every folder will open (note that only folders will be open)

*Hold down Alt+w to start closing all opened folders (notice that only first two folders would close this way, another bug?)

*Repeat with Alt+w and close another 10-20 folders until app_server deadlock.

[diver]

Can't reproduce it in hrev38300 in vbox. Feel free to close.