[gtk] (34 commits) Non-fast-forward update to branch matthiasc/for-master

[Matthias Clasen <matthiasc src gnome org>]

The branch 'matthiasc/for-master' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  86e8e3e... Add a warning when a grab fails
  3a9d71d... Remove GdkSeatGrabPrepareFunc from headers

Commits added to the branch:

  9fa7a47... color chooser: Fix fallout from floatification (*)
  3eea9f3... Merge branch 'color-float-fix' into 'master' (*)
  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 (*)
  76e115b... Add a warning when a grab fails (*)
  767849d... Remove GdkSeatGrabPrepareFunc from headers (*)
  b002572... Merge branch 'wip/otte/dnd' into 'master' (*)
  be25905... Fix gdk docs build (*)
  a0eb7f8... x11: Fix a crash in event handling

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