Overlay: Enabled wireframe drawing for vertex/weight paint

This is a temp hack, so that billrey can use blender 2.8 for
drawing the icons. Hack will be phased out by T54910

release/scripts/startup/bl_ui/space_view3d.py

@@ -3592,6 +3592,14 @@ class VIEW3D_PT_overlay(Panel):
 
         col.prop(view, "show_world")
 
+        if context.mode in {'PAINT_WEIGHT', 'PAINT_VERTEX'}:
+            engine_type = {
+                'PAINT_WEIGHT': 'WeightPaintMode',
+                'PAINT_VERTEX': 'VertexPaintMode',
+            }.get(context.mode)
+            engine_props = scene.collection_properties[engine_type]
+            col.prop(engine_props, "use_wire")
+
         if context.mode in {'PAINT_WEIGHT', 'PAINT_VERTEX', 'PAINT_TEXTURE'}:
             col.prop(view, "show_mode_shade_override")
 

source/blender/draw/modes/shaders/paint_wire_vert.glsl

@@ -10,5 +10,8 @@ void main()
 {
 	gl_Position = ModelViewProjectionMatrix * vec4(pos, 1.0);
 
+	/* Temp hack for william to start using blender 2.8 for icons. Will be removed by T54910 */
+	gl_Position.z -= 0.001;
+
 	finalFlag = data;
 }