Question
Could you give me more details about the Gantt.UpdateMultiSelect function? What is that for?
Answer
You send in a specific time item to the Gantt.UpdateMultiSelect. If the control key is held at the moment, the selection state of the time item will be toggled. If the ctrl is not held, all other time items that might be selected will de-select and the time item in question will be the only one left selected.