Suggestion for focus policy

[mgermerie]

I suggest that we change the focus policy on GlobeView and PlanarView. Here is a little suggestion list for it :

• We could add an optional parameter in View constructor. We could call it autoFocus or hasFocus. It would define whether the view.domElement has the focus when the view is created. I believe it should default to true.
• When the view.domElement is clicked, it should gain focus. This is already the case for both GlobeView and PlanarView.
• When clicking a GUI element (such as widgets or debug menu), the focus should return to the view.domElement :
  • either when releasing the click (mouseup) for most of the GUI elements,
  • or at a time predicted in code for specific elements : for instance, when clicking or hitting enter on a suggestion bellow the search bar.

This would improve the Controls. Indeed, we could capture keyboard events no longer on window but on view.domElement. Therefore, if user have some specific keyboard event management on its webpage, including an iTowns viewer would not break it.
Moreover, it would be the occasion to implement the same focus policy on both PlanarControls and GlobeControls.