On Win I found a free app "Always On Top", in the Cubase Vst Window you un-check "Always On Top(my as#)" top right menu. Run the "Always On Top" app set the HotKey, click the Cubase VST window and hit the HotKey.
Here's one but there are more free ones Always On Top 1.3

For these 2 solutions you just load the VST (instrument or FX) then load the Biab VST (instrument or FX) inside them, this way the Plugin stays on top if there is a flash message or you click on the desktop.
Use MiniHost
Direct Download Links
DropBox
Mac
Win

The other way is using PluginFlipFlop if you already have JBridge
If you use PluginFlipFlop this will also work Biab Plugin Chord Picker Tool Generic v1.2 for Most DAWs