MATLAB: Listbox multi selection without using Ctrl

Question

Hi All

I have a GUIDE listbox in which I select and deselect multiple options regularly. Listbox entry selection unfortunately works like Windows file selection in Explorer; You have to hold down Ctrl if you want to deselect only one file in a selection or want to add one. Can I set the listbox to rather toggle clicked entries? When my customer forgets to hold down Ctrl, all their selections disappear…

Thanks!

Answer 1

Each time they make a selection, the Callback is invoked, and the control's value property is updated to reflect the current selection.

If you keep track of the previous value property then if the new value is scalar (because the user forgot to hold control) then check to see if the new value was present in the previous selection: if it was then update the value property to the old value without the current value, because this is the case where a user clicked on an existing selected value intending to exclude it. If the new value was not present in the previous value then set the new value to be the combination of the old one and the current value, as this is the case of the user clicking on a nonselected value intending to select it.

You might not want to apply this logic if the previous value was scalar and the new one is as well, as that is the ambiguous case: it could be that the user had selected one thing before and clicked something else because they changed their mind, or it could be the case where the user had one thing selected and forgot to hold down control to select the second one.

I recall that I implemented this logic at some point, but my memory of when has gone into hiding so I would have difficulty digging it up.