Custom Toplevels widget

Fixes centering on toplevels.

Need to use fewer hacks, and add equal scale factor.

See if Iced layout system can be improved.

src/widgets/mod.rs

@@ -17,6 +17,8 @@ mod workspace_item;
 pub use workspace_item::workspace_item;
 mod mouse_interaction_wrapper;
 pub use mouse_interaction_wrapper::mouse_interaction_wrapper;
+mod toplevels;
+pub use toplevels::toplevels;
 
 trait Foo {}