Mappings from a source to multiple targets involves a pop-up

[jpav]

Currently, when a source element is involved in multiple mappings to separate targets and the user selects that source element, a pop-up is displayed asking the user to select which mapping they'd like to edit. There are general concerns with pop-ups, such as modality issues and the need to resize or scroll the normally smaller windows. In addition, in the future we expect to support more advanced mappings that would involve multiple source source/target elements, so there is additional concern that representing these mappings textually within the pop-up will become more complicated and harder to understand. It would be nice if there was a way to allow this type of selection to be performed inline within the main window. One possible avenue to investigate would be showing all of the mappings available via the connecting mappings lines and possibly other visual modifications such as showing all target elements involved by collapsing the uninvolved elements in the target tree into some type of collapsed area that can be expanded by explicit user action (e.g., by clicking on a vertical ellipsis icon)