QwtSlider with zero range

[Uwe]

Thought you want to nail a fixed value - why do you have to narrow the borders for this ?
But anyway: a slider with an empty range doesn't make any sense as you don't have a slider position then.

Uwe

[Induriel]

Ok, to give a more complete explanation: our machines are able to pulse some light with a frequency. The frequency can be adjusted by the user in a specific range, set by our service personal. There are some machines which should pulse only on a single frequency, so our service is used to set upper border and lower border to the same value.

Anyway, I had the same use case with Qwt5.2.1, and it worked there (setting upper border and lower border to let's say 50 and slider->value() gives me 50). The behaviour in Qwt6.1.2 is different, slider->value() gives me 0. The range is not empty (may depend on the definition of empty of course), and I think there is a position for the thumb - 50. Even if the thumb cannot move.

Hopefully this explains my problem better. Sorry for the confusion!

Thanks,
Carsten

[Uwe]

Each position of a slider corresponds to a value, and each value to a position - otherwise it doesn't work. So what should happen when all positions of the slider correspond to 50 - where to draw the handle ?
But why not simply setting some valid range and putting the slider into read only mode, when the user sets an empty range ?

Uwe

[Induriel]

I implemented it as you suggested, it works fine.
Thanks for your help,
Carsten