Add "show all controls" button, that allows most of the "set once"
controls to be hidden on small screens. Please feel free to make a
better icon! Could also be hidden if !ANDROID, if you don't like it.
Add pinch and pan gestures, for frequency scrolling and zooming in to
spectrum.
Queue frequencies requested by scrolling, so intermediate frequencies
can be omitted, if device is slow to update its frequency.
Support non-integer pixel ratios.
Add popup sliders for dials.
Add DialogPositioner for dialogs.
Add layout to spectrum markers dialog, so that it can be resized, to fit
on smaller screens.
screen when screen orientation changes.
Add DialPopup to allow dials to adjusted with a slider, which is easier
on touchscreens.
Add TableTapAndHold to support table context menus on touchscreens.
Add sizeToContents in ChannelGUI and FeatureGUI, called when widget is
rolled, so we can remove resizing code from all of the individual
channels and features.
In RollupContents, use minimumSizeHint for calculated size, so that
minimumWidth can come from .ui file.
In DeviceGUI::sizeToContents(), call adjustSize(), so Device GUIs start
out at minimum needed size (which should restore appearance prior to
last patch).
In stackSubWindows, use available space for channels if no
spectrum/features present.
In stackSubWindows, fix spectrum from being sized too big, resulting in
scroll bars appearing.
Reset user-defined channel width in stackSubWindows, when channels are
removed.
Don't stack maximized windows.
There's one hack in Channel/FeatureGUI::maximizeWindow(). It seems that
when maximimzing a window, QOpenGLWidgets aren't always paint properly
immediately afterwards, so the code forces an additional update. I can't
see why the first call to paintGL doesn't work.
