Trivial - Open WD.
- Add "Sequence Marker" element to the scene, select it.
Expected state: there are buttons on the parameters widget: "add", "edit" and "remove". The "add" button is enabled, other buttons are disabled. - Add a new marker group (click the "add" button and fill the dialog).
Expected state: a new group was added, there is no selection in the marker group list, the "add" button is enabled, other buttons are disabled. - Select the added group.
Expected state: the group is selected, all buttons are enabled. - Click the "remove" button.
Expected state: the group is removed (the list is empty), the "add" button is enabled, other buttons are disabled.
Current state: "edit" and "remove" buttons are still enabled. If you click them nothing happens.
