@joyceeariel This is a great idea. I hope Opera implements it.
I ended up just deactivating sidebar. I love the convenience it provides but the occasional convenience does not outweigh the constant interruption as I wait for the sidebar to open and close when I accidently touch it with the mouse. A delay would be wonderful. An option to open it with a deliberate click on some control would be even better.

I know when I want the sidebar. Let me choose.