requested to merge feaneron/gnome-builder:gbsneto/preferences-sidebar-size into main
IdePreferencesWindow currently has a horizontal box handling both headerbars, and another horizontal box handling the sidebar and the page content stack. This works, but allows the sidebar size get out of sync with the left headerbar. Reorganize these boxes to have a vertical box with headerbar and sidebar, and another vertical box with headerbar and page content stack. There's now only a single separator, separating these two vertical boxes.
This is main's setting window:
And this is this branche's settings window: