Perhaps, in the meantime, and getting back to your original question, if anyone wants to alter the height of their spectrum display you can do so simply by *editing .../htdocs/css/openwebrx.css

Look for a line that begins ".openwebrx-spectrum-container" (line #2069 in the file I just viewed) and change the "max-height:" directive in the block below from 50px to your preference - for example 100px.

Do the same for the following block beginning ".openwebrx-spectrum-container.expanded"

This should be all that's needed, you may need to refresh your session and/or restart for the result to be observed.

Note: If you're at all uncertain you would be advised to back up your installation before making any changes.

That said it's an easy change and I'd encourage people to experiment and learn more about their systems. Who knows, one day you may be able to contribute some code back to further improve OpenWebRX.

*A good editor for many Linux distributions is 'nano'.

It's been a while but as I recall I coupled the scale to the waterfall display so it changed appropriately as that was altered.

No-one ever asked for deviation measurement, the image I posted was simply a (then) example of some of the changes I'd made - including the 'peak hold' that Martin was asking about.