Mouse clicks on the debug menu are offset incorrectly while in windowed mode. It see for yourself just hit ALT + Enter to go into windowed mode, hit the maximize button to see the debug menu and try to hover over an element with your mouse.
I believe this is the Unproject() calculation, if you enable the debugCamera at a different DistanceAboveTarget (ex. 25.0f)in the GetRenderEntityBasisP function, your mouse will now need to be at the top of your screen (same place as if the debugCamera was off) to highlight/click on the trees that are almost in the middle of your window/screen now.