Just a guess:
You accidentally detached the tool options with a click-drag on the tab. Lost when you closed Gimp
Restored the tool options using Windows -> Dockable Dialogues -> Tool Options which put the tab in the top left dock.
Look for the lock tab to dock toggle and appiy it. Note it is not global, you have to apply for each tab in turn.
You accidentally detached the tool options with a click-drag on the tab. Lost when you closed Gimp
Restored the tool options using Windows -> Dockable Dialogues -> Tool Options which put the tab in the top left dock.
Look for the lock tab to dock toggle and appiy it. Note it is not global, you have to apply for each tab in turn.