Properties Window:

*The narrowui value was hard coded in all ui scripts, made an user preferences option. Basically this value determines on which area width, it should switch between dual/single column layout. 

ToDo: The Changes only take effect when reloading scripts/restarting Blender (after saving as default). Will maybe add the "Reload Scripts" operator next to the button in the future. 

* Small fix for Fluid Add Button, when in single column mode. Didn't expand like the other "Add" Buttons.

release/scripts/ui/properties_animviz.py

@@ -19,7 +19,7 @@
 # <pep8 compliant>
 import bpy
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 ################################################
 # Generic Panels (Independent of DataType)

release/scripts/ui/properties_data_armature.py

@@ -20,7 +20,7 @@
 import bpy
 from rna_prop_ui import PropertyPanel
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class DataButtonsPanel(bpy.types.Panel):

release/scripts/ui/properties_data_armature_rigify.py

@@ -19,7 +19,7 @@
 # <pep8 compliant>
 import bpy
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class PoseTemplateSettings(bpy.types.IDPropertyGroup):

release/scripts/ui/properties_data_bone.py

@@ -20,7 +20,7 @@
 import bpy
 from rna_prop_ui import PropertyPanel
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class BoneButtonsPanel(bpy.types.Panel):

release/scripts/ui/properties_data_camera.py

@@ -20,7 +20,7 @@
 import bpy
 from rna_prop_ui import PropertyPanel
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class DataButtonsPanel(bpy.types.Panel):

release/scripts/ui/properties_data_curve.py

@@ -20,7 +20,7 @@
 import bpy
 from rna_prop_ui import PropertyPanel
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class DataButtonsPanel(bpy.types.Panel):

release/scripts/ui/properties_data_empty.py

@@ -19,7 +19,7 @@
 # <pep8 compliant>
 import bpy
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class DataButtonsPanel(bpy.types.Panel):

release/scripts/ui/properties_data_lamp.py

@@ -20,7 +20,7 @@
 import bpy
 from rna_prop_ui import PropertyPanel
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class LAMP_MT_sunsky_presets(bpy.types.Menu):

release/scripts/ui/properties_data_lattice.py

@@ -20,7 +20,7 @@
 import bpy
 from rna_prop_ui import PropertyPanel
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class DataButtonsPanel(bpy.types.Panel):

release/scripts/ui/properties_data_mesh.py

@@ -20,7 +20,7 @@
 import bpy
 from rna_prop_ui import PropertyPanel
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class MESH_MT_vertex_group_specials(bpy.types.Menu):

release/scripts/ui/properties_data_metaball.py

@@ -20,7 +20,7 @@
 import bpy
 from rna_prop_ui import PropertyPanel
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class DataButtonsPanel(bpy.types.Panel):

release/scripts/ui/properties_data_modifier.py

@@ -19,7 +19,7 @@
 # <pep8 compliant>
 import bpy
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 narrowmod = 260
 
 

release/scripts/ui/properties_game.py

@@ -19,7 +19,7 @@
 # <pep8 compliant>
 import bpy
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class PhysicsButtonsPanel(bpy.types.Panel):

release/scripts/ui/properties_material.py

@@ -20,7 +20,7 @@
 import bpy
 from rna_prop_ui import PropertyPanel
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 def active_node_mat(mat):

release/scripts/ui/properties_object.py

@@ -20,7 +20,7 @@
 import bpy
 from rna_prop_ui import PropertyPanel
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class ObjectButtonsPanel(bpy.types.Panel):

release/scripts/ui/properties_object_constraint.py

@@ -19,7 +19,7 @@
 # <pep8 compliant>
 import bpy
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class ConstraintButtonsPanel(bpy.types.Panel):

release/scripts/ui/properties_particle.py

@@ -25,7 +25,7 @@ from properties_physics_common import effector_weights_ui
 from properties_physics_common import basic_force_field_settings_ui
 from properties_physics_common import basic_force_field_falloff_ui
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 def particle_panel_enabled(context, psys):

release/scripts/ui/properties_physics_cloth.py

@@ -19,7 +19,7 @@
 # <pep8 compliant>
 import bpy
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 from properties_physics_common import point_cache_ui
@@ -75,7 +75,7 @@ class PHYSICS_PT_cloth(PhysicButtonsPanel):
             # add modifier
             split.operator("object.modifier_add", text="Add").type = 'CLOTH'
             if wide_ui:
-                split.column()
+                split.label()
 
         if md:
             cloth = md.settings

release/scripts/ui/properties_physics_common.py

@@ -18,10 +18,10 @@
 
 # <pep8 compliant>
 
-narrowui = 180
-
 import bpy
 
+narrowui = bpy.context.user_preferences.view.properties_width_check
+
 #cachetype can be 'PSYS' 'HAIR' 'SMOKE' etc
 def point_cache_ui(self, context, cache, enabled, cachetype):
     layout = self.layout

release/scripts/ui/properties_physics_field.py

@@ -19,7 +19,7 @@
 # <pep8 compliant>
 import bpy
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 from properties_physics_common import basic_force_field_settings_ui

release/scripts/ui/properties_physics_fluid.py

@@ -19,7 +19,7 @@
 # <pep8 compliant>
 import bpy
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class PhysicButtonsPanel(bpy.types.Panel):
@@ -42,7 +42,7 @@ class PHYSICS_PT_fluid(PhysicButtonsPanel):
         md = context.fluid
         wide_ui = context.region.width > narrowui
 
-        split = layout.split(percentage=0.5)
+        split = layout.split()
 
         if md:
             # remove modifier + settings

release/scripts/ui/properties_physics_smoke.py

@@ -19,7 +19,7 @@
 # <pep8 compliant>
 import bpy
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 from properties_physics_common import point_cache_ui

release/scripts/ui/properties_physics_softbody.py

@@ -19,7 +19,7 @@
 # <pep8 compliant>
 import bpy
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 from properties_physics_common import point_cache_ui

release/scripts/ui/properties_render.py

@@ -19,7 +19,7 @@
 # <pep8 compliant>
 import bpy
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class RENDER_MT_presets(bpy.types.Menu):

release/scripts/ui/properties_scene.py

@@ -20,7 +20,7 @@
 import bpy
 from rna_prop_ui import PropertyPanel
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class SceneButtonsPanel(bpy.types.Panel):

release/scripts/ui/properties_texture.py

@@ -20,7 +20,7 @@
 import bpy
 from rna_prop_ui import PropertyPanel
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class TEXTURE_MT_specials(bpy.types.Menu):

release/scripts/ui/properties_world.py

@@ -20,7 +20,7 @@
 import bpy
 from rna_prop_ui import PropertyPanel
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class WorldButtonsPanel(bpy.types.Panel):

release/scripts/ui/space_image.py

@@ -19,7 +19,7 @@
 # <pep8 compliant>
 import bpy
 
-narrowui = 180
+narrowui = bpy.context.user_preferences.view.properties_width_check
 
 
 class IMAGE_MT_view(bpy.types.Menu):

release/scripts/ui/space_userpref.py

@@ -165,6 +165,13 @@ class USERPREF_PT_interface(bpy.types.Panel):
         sub.enabled = view.show_mini_axis
         sub.prop(view, "mini_axis_size", text="Size")
         sub.prop(view, "mini_axis_brightness", text="Brightness")
+        
+        col.separator()
+        col.separator()
+        col.separator()
+        
+        col.label(text="Properties Window:")
+        col.prop(view, "properties_width_check")
 
         row.separator()
         row.separator()

source/blender/editors/interface/resources.c

@@ -1488,6 +1488,11 @@ void init_userdef_do_versions(void)
 	if (U.v2d_min_gridsize == 0) {
 		U.v2d_min_gridsize= 35;
 	}
+	
+	/* Single Column UI Value */
+	if (U.propwidth == 0) {
+		U.propwidth = 200;
+	}
 
 	/* funny name, but it is GE stuff, moves userdef stuff to engine */
 // XXX	space_set_commmandline_options();

source/blender/makesdna/DNA_userdef_types.h

@@ -362,6 +362,8 @@ typedef struct UserDef {
 
 	short scrcastfps;		/* frame rate for screencast to be played back */
 	short scrcastwait;		/* milliseconds between screencast snapshots */
+	
+	short propwidth, pad[3]; /* Value for Dual/Single Column UI */
 
 	char versemaster[160];
 	char verseuser[160];

source/blender/makesrna/intern/rna_userdef.c

@@ -2052,6 +2052,13 @@ static void rna_def_userdef_view(BlenderRNA *brna)
 	RNA_def_property_enum_funcs(prop, NULL, "rna_userdef_timecode_style_set", NULL);
 	RNA_def_property_ui_text(prop, "TimeCode Style", "Format of Time Codes displayed when not displaying timing in terms of frames");
 	RNA_def_property_update(prop, 0, "rna_userdef_update");
+	
+	/* Properties Window */
+	prop= RNA_def_property(srna, "properties_width_check", PROP_INT, PROP_NONE);
+	RNA_def_property_int_sdna(prop, NULL, "propwidth");
+	RNA_def_property_range(prop, 150, 400); 
+	RNA_def_property_ui_text(prop, "Width Check", "Dual Column layout will change to single column layout when the width of the area gets below this value (needs restart to take effect)");
+	RNA_def_property_update(prop, 0, "rna_userdef_update");
 }
 
 static void rna_def_userdef_edit(BlenderRNA *brna)