UI: Allow Some Buttons to Scale Width With Text Style

Allow some View3D buttons to change their width according to content
and Text Styles, rather than be fixed amount of UI_UNIT_X. Examples
include "Object Mode", "Transform Orientation", "Grease Pencil Layers",
"Texture Slots", "Vertex Groups", "Attribute", etc.

Pull Request: https://projects.blender.org/blender/blender/pulls/119223

scripts/startup/bl_ui/space_view3d.py

@@ -209,7 +209,6 @@ class VIEW3D_HT_tool_header(Header):
 
             layout.label(text="Layer:")
             sub = layout.row()
-            sub.ui_units_x = 8
             sub.popover(
                 panel="TOPBAR_PT_gpencil_layers",
                 text=text,
@@ -638,7 +637,6 @@ class VIEW3D_HT_header(Header):
             row = layout.row(align=True)
 
             sub = row.row()
-            sub.ui_units_x = 4
             sub.prop_with_popover(
                 orient_slot,
                 "type",
@@ -751,7 +749,6 @@ class VIEW3D_HT_header(Header):
         act_mode_i18n_context = bpy.types.Object.bl_rna.properties["mode"].translation_context
 
         sub = row.row(align=True)
-        sub.ui_units_x = 5.5
         sub.operator_menu_enum(
             "object.mode_set", "mode",
             text=iface_(act_mode_item.name, act_mode_i18n_context),
@@ -946,7 +943,6 @@ class VIEW3D_HT_header(Header):
             color_type = shading.color_type
 
             row = layout.row()
-            row.ui_units_x = 6
             row.active = is_paint_tool and color_type == 'VERTEX'
 
             if context.preferences.experimental.use_sculpt_texture_paint:
@@ -964,12 +960,10 @@ class VIEW3D_HT_header(Header):
 
         elif object_mode == 'VERTEX_PAINT':
             row = layout.row()
-            row.ui_units_x = 6
             row.popover(panel="VIEW3D_PT_slots_color_attributes", icon='GROUP_VCOL')
 
         elif object_mode == 'WEIGHT_PAINT':
             row = layout.row()
-            row.ui_units_x = 6
             row.popover(panel="VIEW3D_PT_slots_vertex_groups", icon='GROUP_VERTEX')
 
         elif object_mode == 'TEXTURE_PAINT':
@@ -977,7 +971,6 @@ class VIEW3D_HT_header(Header):
             icon = 'MATERIAL' if tool_mode == 'MATERIAL' else 'IMAGE_DATA'
 
             row = layout.row()
-            row.ui_units_x = 9
             row.popover(panel="VIEW3D_PT_slots_projectpaint", icon=icon)
             row.popover(panel="VIEW3D_PT_mask", icon='MOD_MASK', text="")
         else: