Entered data is not accepted when the same value is open in two dialogs

[zevv]

Not sure if the title properly describes the issue. To reproduce:

• Start a clean ngscopeclient
• In the filter graph, add a Sine module. Sine_1 dialog now pops up in a new window. Leave that open.
• Switch back to the Filter graph tab
• Right click on the sine module and open 'Parameters' section
• Try to enter a new value in the frequency field

The new value will not be accepted, it will be replaced with the old value as soon as the box leaves focus or when input is completed. Changing the same parameter in the initial Sine_1 popup window does work however.

[azonenberg]

I think the better fix for this is to not allow dual dialogs to be open, rather than trying to sync between them. Maybe auto close the dialog when you open the popup or something.

But there's also work to be done in terms of cleaning up this part of the UI. The auto spawning dialogs mostly date to the era before the filter graph editor existed. I feel like we probably don't want to open them by default now.