Cannot remove surplus assignment from objective with zero effort estimate

[amdw]

If you create an objective with a non-zero estimate, add an assignment, and then change the effort estimate to zero, then the assignment turns red (as it should), but there is no way to remove it. If you click on the red assignment then nothing happens.

This is because enableAssignButton() on the objective component returns false if it has a zero effort estimate, so there is no way to bring up the assignment dialog.

If you want to remove the assignment, you have to change the effort estimate to a non-zero value again, open the assignment dialog to remove the assignment, and then change the effort estimate back to zero again.

One possible fix would be: when the user clicks on the red assignment, instead of opening the assignment dialog, open a modal dialog that simply asks the user if they want to remove the assignment.