[gtk] (28 commits) ...Merge branch 'wip/otte/dnd' into 'master'

[Benjamin Otte <otte src gnome org>]

Summary of changes:

  f656cbd... Ensure all natives request at least a 1px wide surface (*)
  612ba7e... widget: Don't check for natives (*)
  418bdc8... sizerequest: Stop clamping for_size to natural size (*)
  4128ee8... widget: Pull margin computation out of adjust_allocation (*)
  6f73a75... widget: Simplify adjust_allocation() (*)
  be4b34a... events: Use GdkDrop as event sequence (*)
  fc43ec0... gtk: Bubble drag events like motion events (*)
  9223d1e... eventcontrollermotion: Fix docs (*)
  34e5f36... Add GtkDropControllerMotion (*)
  2a8fd25... testsuite: Check proper notify emissions, too (*)
  d680e2e... Port simple cases to GtkDropControllerMotion (*)
  a5e2275... stackswitcher: Use GdkDropControllerMotion (*)
  a12e563... main: Don't synthesize crossing events when nothing changed (*)
  ce3ed45... surface: Inline function (*)
  e3aee62... drop: Guard variable with correct compiler flags (*)
  f9b7825... device: Inline function into return_if_fail() (*)
  99fc318... comboboxtext: Inline functions into return_if_fail() (*)
  42d71f1... combobox: Inline variables into return_if_fail() (*)
  2e941ac... filesystemmodel: Guard variable with correct compiler flags (*)
  eb70173... levelbar: Guard function by right compiler macros (*)
  2cb0007... iconview: Inline variables into return_if_fail() (*)
  0c4c88b... scrolledwindow: Inline variable into return_if_fail() (*)
  d9e3eaa... treeview: Guard code by right compiler macros (*)
  18d7187... testsuite: Don't use return_if_fail() (*)
  6f0a0ce... testsuite: Don't use g_return_if_fail() (*)
  9d915ff... treeviewcolumn: Inline variable into return_if_fail() (*)
  8a098b1... tests: Guard variables with necessary macros (*)
  b002572... Merge branch 'wip/otte/dnd' into 'master'

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