Sorry that I might not have made this clear enough, but this is NOT what "Toggle" is supposed to do. You said toggle will bring the Fences to front and disable the "Normal" desktop function --- this is perfectly fine. However, after you double-click an application in Fences and open that application, the desktop function is still disabled --- this is a bug.
The reason to use "Toggle" is to quickly show Fences and open an application in Fences. It's meaningless to keep the desktop still frozen after the user has opened an application in Fences. Earlier versions of Fences did not have this issue. This issue only occurred after updating to Fences 4.
This bug also causes another problem. Sometime you want to use the "toggle" hotkey to bring the desktop to front, but it won't work, because the hotkey actually turns off the previous toggle.
The issue here is the "toggle" should be turned off once you select an application from Fences. For example, "Alt-Tab" is the hotkey to toggle between windows in the windows systems, but once you select a window, nothing is frozen anymore.