UML modelling editor should allow reordering attributes/methods in elements.

[lukaskollmer]

(Note: Everything here applies to both attributes and methods.)

Is your feature request related to a problem?

When modelling e.g. a class via UML, I prefer to have related attributes close to each other (for example, a list's length and capacity attributes should not have other unrelated attributes in between). Currently, in Artemis' UML modelling tool, it is not possible to change the order of attributes, and you have to manually copy and paste the names around.
This also becomes an issue when you want to insert an attribute at a specific location between other attributes.

Describe the solution you'd like

1. There should be a "drag" button next to an attribute's row, to drag the row to a different location within the list of attributes.
2. There should be an option to insert between existing items, instead of only being able to append to the back of the list. This could be implemented by showing a plus button when hovering with the mouse over the vertical space between two attributes' delete buttons.

Describe alternatives you've considered

• The reordering could be implemented via up/down buttons. This would probably be a lot easier to implement, but also (imo) a somewhat worse UX.
• Having an option to insert at a specific location is probably irrelevant if you can move stuff around.

Additional context

n/a

[krusche]

Moved to the Apollon repository. We like to keep Apollon as simple as possible and would like to avoid features that clutter the user interface. But we could think about a lightweight solution