This was marked as solved but I didn't see any mention of how you fixed it. Any links to the solution would greatly appreciated as this was the first post that appeared when I searched the forum for this keyboard shortcut problem. Thanks.
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Settings Manager -> Keyboard -> Application Shortcuts change xfce4-popup-whiskermenu to something else I used Alt+Super L that let me set up the other keys like Super L left & right arrow for controlling the windows and still get the menu with Alt+Super L. (Super L is the left Windows key.)
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Settings Manager -> Keyboard -> Application Shortcuts change xfce4-popup-whiskermenu to something else I used Alt+Super L that let me set up the other keys like Super L left & right arrow for controlling the windows and still get the menu with Alt+Super L. (Super L is the left Windows key.)