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modal_events.htm
Navigation:  Language Reference > App B - Events >====== Modal Events ====== Previous pageReturn to chapter overviewNext page

NewC7.jpg

The following Events must always be treated as “modal”:

EVENT:LoseFocus

EVENT:GainFocus

EVENT:Dragging

EVENT:Contracting

EVENT:Expanding

EVENT:PreAlertKey

EVENT:TabChanging

EVENT:Move

EVENT:Size

EVENT:Restore

EVENT:Maximize

EVENT:Iconize

EVENT:Sized

EVENT:Selected

EVENT:Selecting

Also, if a list box has the IMM attribute

EVENT:ScrollUp

EVENT:ScrollDown

EVENT:PageUp

EVENT:PageDown

EVENT:ScrollTop

EVENT:ScrollBottom

EVENT:ScrollTrack

EVENT:ScrollDrag

When we refer to an event as “modal”, it means that until the event is completed the runtime library can't continue its normal work. The main rule for writing code that responds to these events is that the event must be completed within a “finite” period of time.

This means that the code you write for handling “modal” events should not invoke dialogs, include inner ACCEPT loops, call Message Boxes, or anything similar that would prevent the ACCEPT loop from completing the processing of the event. When your program needs to do something like this upon processing one of these events, a custom event should be posted to the front of the event queue. For example:

CASE EVENT()

OF EVENT:GainFocus

POST(MyGainFocus,,, TRUE) !Post a user defined event to handle GainFocus action

OF MyGainFocus

<;perform actions for gaining focus>

END

modal_events.htm.txt · Last modified: 2021/04/15 15:57 (external edit)