Actually i fixed it myself. Went to Tools, Preferences, Appearance.
Clicked on Reset Docking and Reset toolbars button to reset to default configurataion. the error went away.
Control 'dxDockToDoPanel' has no parent window.
I just upgraded my PLSQL Developer Version from 10 to 11 and I am getting the above error.
I searched in the forum and found this link:https://forums.allroundautomations.com/ubb/ubbthreads.php?ubb=showflat&Number=39882
I deleted the Docking3 and...