Druid: Missing request_paint somewhere.

[totsteps]

I am not sure how to title this issue, but when incrementing or decrementing the menu item value via the context menu in multi-win example, the custom menu in the menu-bar gets updated instantly but there's a slight random delay when updating the label value.

Tested on macOS.

An example and discussion can be found in zulip chat.

As noted by Colin Rofls this is missing request_paint or similar somewhere.

[emigr2k1]

After clicking on the context menu item, AppState::handle_system_cmd gets called but this function doesn't call do_update as other functions such as do_window_event do.
I'm not familiar with druid's internals so I don't know if calling do_update in handle_system_cmd is a good fix.

[totsteps]

@emigr2k1 thanks for the PR.
I can confirm that this has been fixed.

This issue can be closed unless @cmyr has some other thoughts.