[gtk] (9 commits) ...Merge branch 'matthiasc/for-master' into 'master'

[Matthias Clasen <matthiasc src gnome org>]

Summary of changes:

  a39e519... inspector: Clear overlays on unroot (*)
  a88e5a5... columnview: Fix some issues with column resizing (*)
  39baf4f... columnview: Fix more issues with column resizing (*)
  1976df1... columnview: Make resize cursors reliable (*)
  98b66ac... columview: Implement double-click to reset headers (*)
  25d0fb4... columview: Make resize area a bit larger (*)
  f3fe181... Adwaita: Put column separators on the left (*)
  81ee273... columnview: Make right-aligned content work (*)
  2359510... Merge branch 'matthiasc/for-master' into 'master'

(*) This commit already existed in another branch; no separate mail sent