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How to detect Ctrl key pressed during list selection?

EvanShultz

I have a SKILL form with a LIST-type FIELD in it. I would like the list to be multi-select and do something different if the user is holding down Ctrl when selecting an item vs not holding down any key. Is this possible? Nothing in the form callback for the list element indicates a modifier key is pressed (that I can see, anyway) and I'm not sure where else to look.

I write the subject of this discussion generic but the concept should apply to other modifier keys (for example Alt) and other form elements.

  • EvanShultz

    Maybe I should explain what I'm thinking. The list on the form currently only supports a single selection, but I was thinking of an enhancement that would require multiple selection.

    I currently print the form like this:

    fprintf(port "FIELD CompList\n")
    fprintf(port "FLOC 2 8\n")
    fprintf(port "LIST \"\" 42 10\n")
    fprintf(port "ENDFIELD\n")

    From reading the BNF docs I figured out I can add this line to this section of the form to make it multi-select:

    fprintf(port "OPTIONS multiselect\n")

    But I haven't figured out what that buys me. Multiple items in the form are then selected, but the form callback only reports the item I clicked on. That means I can't figure out if the user selected an item with Ctrl pressed, and so I need to add the clicked item to the select set, or if the user didn't press the Ctrl key and I need to clear the select set and then only add the clicked item.

    I don't find an Allegro dialog with this user paradigm (they all have separate "selected" and "unselected" lists, like the "Find by Name or Property" form) so maybe I should rethink how I was approaching this form?

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