Fix: VSE preview display channel / overexposed fields wrongly disabled

When proxy render size was set to Scene or None, the UI wrongly
disabled more following UI fields, instead of just the "use proxies"
field.

Pull Request: https://projects.blender.org/blender/blender/pulls/144988

scripts/startup/bl_ui/space_sequencer.py

@@ -2830,10 +2830,11 @@ class SEQUENCER_PT_view(SequencerButtonsPanel_Output, Panel):
         col.prop(st, "proxy_render_size")
 
         col = layout.column()
-        col.prop(st, "use_proxies")
         if st.proxy_render_size in {'NONE', 'SCENE'}:
             col.enabled = False
+        col.prop(st, "use_proxies")
 
+        col = layout.column()
         col.prop(st, "display_channel", text="Channel")
 
         if st.display_mode == 'IMAGE':