LabVIEW disabled Slider is enabled

Question

I have a large problem disabling a slider in LabVIEW. Here is my minimal example:

I have a simple Slider, which is disabled and grayed out if the value is higher than 5. Otherwise the Slider is enabled.

If I drag the slider higher than 5, the Slider gets grayed out. But I am still able to move the slider around and change the value. Only after I dropped the Slider, the Slider is disabled to use.

In my opinion, this is a large bug of LabVIEW. Is there any way to disable the Slider correct during drag?

Thank you for your answers!

Additional information: Like I said, the snippet is only my minimal example to show the basic problem. In my application the following is happening:

I have s statemachine with a state that enables the Slider and a state that disables my Slider. The state can change every moment, so it´s possible, the user is using the slider at the moment of statechange --> moment of disabling. At this moment the slider should be disabled (it only gets grayed out) directly ... not after releasing it. So limiting the maximum is not real target. I want to prohibit all slider actions for a user.

"Link to question asked on NI Discussion Forums"

Answer 1

As suggested by Alexander_Sobolev on the NI forum (but I promise I thought of it independently!), you can end the slider drag by generating a mouse up event. On Windows you can do this with Simulate Mouse.vi from the NI site, which calls mouse_event from user32.dll:

Note that one of that VI's mouse position inputs is erroneously marked as 'Required'; I fixed that before creating the code above.

I do think this is a UI technique that should only be used if it's really justified by the requirements of the system, and if the users will understand why it works like that; otherwise it could make for a frustrating and annoying user experience. I don't think it's a bug, rather a design decision, because the opposite behaviour could be equally undesired in other circumstances.

Answer 2

This appears to be strange behavior as the Value Change event is triggered while the mouse button is held down even when the control is Disabled & Grayed Out.

One way I can think of to limit the value would be to update the Data Entry Limits Maximum property for this control and setting the Response to Value Outside Limits for Maximum to be Coerce.

Answer 3

I guess you could set the slider value to 5 inside the case structure, alongside the greying out, by adding another property node. This should keep the slider stuck at 5, if the user tries to pull it above.