In the current implementation, the main UI will be blocked after the uninstaller is launched. Put the uninstall process in a thread to avoid that, and popup a message while trying to launch multiple uninstallers.
-- v2: appwiz.cpl: Handle WM_CLOSE and WM_COMMAND(IDCANCEL) in the support info dialog. appwiz.cpl: Process messages while waiting for the uninstaller to terminate.