When using a mousedown event listener on a slider for checking something and you want to interrupt the whole process when the checking result is true or false by opening a yes/no dialog, the dialog opens but you can still drag the slider in the panel.
Shouldn’t the modal state of the dialog interrupt the interaction with the panel?
This only happens when you keep holding the mouse button down. If you just click on the slider everything is fine and the panel is “unreachable” → the dialog is in a true modal state. Same after holding the mouse button down and releasing.
It doesn’t really sound like the greatest UX to cut off the users interaction to show a dialog. After all, his interaction is not yet finished if the mouse is still down, so he might change his mind and drag the slider some more.
I’d recommend to only show the dialog after the mousedown or change/input event, so that the user actually finished his dragging process.
That is not the point, just an example.