OpenWebRX 'Transparent' control panel
Over on the OpenWebRX IO group there has been some recent discussions about various enhancements to the GUI.
One of the features implemented by the OpenWebRX user " ivanmarcus" (including at last a spectrum display, Yehay) was to add a 'Transparent' option to the main control panel.
Here's a side by side comparison.
I think it works quite well, and is a bit less intrusive, but that's just my opinion.