Scroll automatically to wigdet when created

When adding a new widget, the window of the workspace should scroll automatically where the new widget has just been created.

Currently this is not the case, which requires if we have a lot of open widget, and that we are very low in the work area to manually move up to the top. Because by default the new added widgets are always displayed at the top. We could change this for example by inserting the widget in a space closest to the active area (TBD)