In a piece of desktop software, I have a around 20 items.
These items should be shown in a list, which fits on the screen.
The user should be able to select exactly two items in the list, then, a diff-like result is shown in a user control next to the list.
What patterns would be nice to use here, so that the count of actions necessary to select two items is minimized?
Due to the resonance and the questions in the comments, here some context.
The program is about comparing trees.
In my case, the user would usually select random items, but I would like to have a nice solution for both cases, selecting two random items or keeping one item selected and changing the other item.
The items themselves represent the trees, however a short tag is available for each item which would be shown in the list.
For the diff, both trees might be shown side-by-side, wheres the nodes which are missing in the other tree are highlighted, for example like this:
The program is going to be used by computer scientists in academia, so elderly people or children are not of concern.