Fix egui focus edge cases

[thmxv]

• When starting to orbit, this continue to work even when the pointer move to over a egui window/area
• When the mouse click and drag operation start in an egui window/area the camera does not start to orbit when getting out of the area and in the viewport

[Plonq]

Thanks! I've pushed a commit that adds a side panel and a moveable window to the egui example, to actually show all the different ways to interact with egui. This showcases your fix better too.