While the Whisker menu is invoked by <Super L> key, (start button), it seems to conflict with Super+D When i type Super+D (fastly), the Whisker menu 'sometimes' opens. From the url https://forums.linuxmint.com/viewtopic.php?f=90&t=227034&p=1198600#p1198600 it is stated that when the Whisker menu has shortcut <Super L>, then Super+D to show desktop doesn't work as intended. However, when the shortcut is changed to Super+M or so, then it works well. Such keybindings, work well in Cinnamon desktop menu well, but there is a problem with Whisker menu keybinding. P.S. Note that when start is pressed along with D (or any other key) and released then it should not be taken to invoke Whisker menu. That is, when start (Super) key is pressed and immediately another key is pressed and both are released, the Whisker menu should not be fired. Only, when start alone is pressed and released without any intermediate key between start press and start release, should the Whisker menu be fired. Note: Start=<Super L>
I don't know if I will be able to fix this. I had to add a messy hack to be able to use Super_L by itself to open Whisker Menu, and that is probably what is causing the conflict. The core issue is that you normally can't use just Super_L by itself as a shortcut in Xfce.
As it turns out, you can use just Super_L by itself, but then you can't have another shortcut that uses Super_L without conflict. This is a known bug in the Xfce keyboard shortcuts. *** This bug has been marked as a duplicate of bug 7845 ***
Actually its not a bug. I think this is the design in XFCE. Unfortunately =(