UI: Gray out fade inactive geometry overlay slider when off

The slider should be inactive when the setting is turned off like
the wireframe slider.

release/scripts/startup/bl_ui/space_view3d.py

@@ -6102,8 +6102,10 @@ class VIEW3D_PT_overlay_geometry(Panel):
 
         col.prop(overlay, "show_face_orientation")
         row = col.row(align=True)
+
         row.prop(overlay, "show_fade_inactive", text="")
         sub = row.row()
+        sub.active = overlay.show_fade_inactive
         sub.prop(overlay, "fade_inactive_alpha", text="Fade Inactive Geometry")
 
         # sub.prop(overlay, "show_onion_skins")