Single column focus mode

[clark800]

Double-clicking on a column title could expand the column to the full width, hiding all other columns. In this state, the column could have a back button to return to the full view, and double clicking could also return to the full view. Editing a column name could be triggered through the column's popup menu.

The motivation for this is that there are different levels of planning. Say the columns are "Phase 1", "Phase 2", and "Phase 3". First you decide which tasks belong in each phase, and then you zoom in and decide how to order tasks within each phase, or you are working on the tasks within that phase. In the latter cases, you don't really want to be distracted by the future phases, and it helps to get more width for each task when they are collapsed and have long first lines.