I am using the overview feature. After zoom-in/zoom-out I click to fit-to-view it fits to view but if I again bymistakely click on fit-to-view it toggles how can I fix this?
That is intentional behavior – to make it easy for the user to temporarily see everything and then switch back to the viewport that they had before. By default the CommandHandler.zoomToFit command is invoked by Shift-Z.
You can just call Diagram.zoomToFit if you prefer not to use the command which toggles.
Thank you, Walter