Pose: make pose-bone xray usable in wpaint mode

Update UI, draw-manager and operator to support with pose-bone-xray
when in weight paint mode.

release/scripts/startup/bl_ui/space_view3d.py

@@ -4812,11 +4812,16 @@ class VIEW3D_PT_overlay_pose(Panel):
 
     @classmethod
     def poll(cls, context):
-        return context.mode == 'POSE'
+        mode = context.mode
+        return (
+            (mode == 'POSE') or
+            (mode == 'PAINT_WEIGHT' and context.active_object.find_armature())
+        )
 
     def draw(self, context):
         layout = self.layout
         view = context.space_data
+        mode = context.mode
         overlay = view.overlay
         display_all = overlay.show_overlays
 
@@ -4824,11 +4829,15 @@ class VIEW3D_PT_overlay_pose(Panel):
         col.active = display_all
         col.prop(overlay, "show_transparent_bones")
 
-        row = col.row()
-        row.prop(overlay, "show_bone_select", text="")
-        sub = row.row()
-        sub.active = display_all and overlay.show_bone_select
-        sub.prop(overlay, "bone_select_alpha", text="Fade Geometry")
+        if mode == 'POSE':
+            row = col.row()
+            row.prop(overlay, "show_bone_select", text="")
+            sub = row.row()
+            sub.active = display_all and overlay.show_bone_select
+            sub.prop(overlay, "bone_select_alpha", text="Fade Geometry")
+        else:
+            row = col.row()
+            row.prop(overlay, "show_bone_select")
 
 
 class VIEW3D_PT_overlay_edit_armature(Panel):
@@ -5461,8 +5470,8 @@ classes = (
     VIEW3D_PT_overlay_edit_mesh_developer,
     VIEW3D_PT_overlay_edit_curve,
     VIEW3D_PT_overlay_edit_armature,
-    VIEW3D_PT_overlay_pose,
     VIEW3D_PT_overlay_paint,
+    VIEW3D_PT_overlay_pose,
     VIEW3D_PT_overlay_sculpt,
     VIEW3D_PT_pivot_point,
     VIEW3D_PT_snapping,