UI

* Fix buttons jumping around when resizing and zoom. Part of this was
  adding a tiny a 0.001f offset in UI_view2d_view_ortho, otherwise the
  rounding is unpredictable (used to be 0.375f, but that was disabled).
* Fix various issues with zooming, panning panels.  V2D_LOCKOFS_X/Y is
  now taken into account in more places in the view2d code, to avoid
  zooming into the center or panning out of the view.
* Remove "Free" align mode in buttons window (it's not really useful).

* View3D/Graph/Image editors now use the same PanelType system as the
  buttons window, means some deprecated panel code could be removed.
* Some small visual tweaks for panels.
* View 2D Reset operator (Home key), to reset zoom and panning for panels.

* Added argument to set number buttons as sliders (slider=True for itemR).
* Ignore labels for button alignment (doesn't look right).
* Fix some use of context.main in py scripts, should get data from active
  object instead.
* Fix autotexspace -> auto_texspace in py script.

source/blender/editors/interface/interface_api.c

@@ -89,6 +89,7 @@ void RNA_api_ui_layout(StructRNA *srna)
 	parm= RNA_def_string(func, "property", "", 0, "", "Identifier of property in data.");
 	RNA_def_property_flag(parm, PROP_REQUIRED);
 	RNA_def_boolean(func, "expand", 0, "", "Expand button to show more detail.");
+	RNA_def_boolean(func, "slider", 0, "", "Use slider for numeric values.");
 
 	func= RNA_def_function(srna, "items_enumR", "uiItemsEnumR");
 	parm= RNA_def_pointer(func, "data", "AnyType", "", "Data from which to take property.");