I recently had a clever idea. As with a lot of my clever ideas, it doesn't seem to work.
I have a bunch of UI elements and want to react to changes to their values via Event Structure. Instead of statically linking all of them into their own case or statically linking them all into a single case (and then somehow working backwards to find out which instance was triggered) I decided to create a callback VI for each control, initialise it with an Index field and then use it as a passthroughvia User Event, effectively adding an "Index" field to the Event received in the Event Structure.
Doesn't work.
When I create the Callback VI for a "Value Changed" Event, the "Old Value" and "NewValue" are not available (These should be in "Event Data", right, but the connector pane is empty - no such control on the FP). Yes, I could go via the control reference to get the value, but that completely destroys the performance of the code.
A callback VI for "Mouse Down" for example DOES include the Event Data. Here, the "Event Data" control is present and connected to the FP Terminals.
I can't believe I never ran into this before.
Edit: Changed Title. Where on earth did the Forums get the original title from?