Describe the bug
When calling Layer.isCollapsed = true/false or Layer.isExpanded = true/false the timeline is not updated, and the groups remain in their original state.

To Reproduce

1. Select a layer
2. Call app.layer.isCollapsed = false on an Expanded Group
3. The timeline folder icon will update properly, but the group.layers will still be visible in the timeline.
4. Clicking the expand/collapse button in the timeline will not do anything the first time you click, apart from change the icon. This is likely because, as far as Aseprite knows, the Collapse/Expand commands have happened, and clicking it again will turn it back to the state that it is already in.

Expected behavior
It collapses or expands the group depending on true/false.

Screenshots

Aseprite & System (please complete the following information):

• Aseprite: v1.3.14.4
• System: Windows 10
• Extensions: :')

Additional context
It is not an app.command.Refresh() issue, that does not update the timeline.