[gtk] (14 commits) ...Merge branch 'wip/otte/for-master' into 'master'

[Benjamin Otte <otte src gnome org>]

Summary of changes:

  4313c47... textview: Fix copy/paste error (*)
  8fc360d... imcontextwayland: Fix copy/paste error (*)
  18b011a... tests: Add a test for changing the hovered widget (*)
  38dcc8f... mountoperation-x11: Fix copy/paste thinko (*)
  f6b11a5... build: Add more useful warning flags (*)
  9fedcec... rbtree: Simplify code (*)
  dc86c74... rbtree: Simplify macros (*)
  a4ed6fd... device: Handle missing axis (*)
  fdd4630... icontheme: Don't crash on icon lookup failure (*)
  4e88d5a... notebook: Don't crash on drags not coming from a notebook (*)
  7dce9e4... treerbtree: Use for loops (*)
  4be4799... icontheme: Remove unused parameter (*)
  e356d59... build: Add -Wnull-dereference (*)
  89e5b8c... Merge branch 'wip/otte/for-master' into 'master'

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