I've been suffering with really small icons in the toolbars with TCad ever since I started using high DPI monitors. I was talking with a engineer at Microsoft about this and they asked if I had set the system to override the application for High DPI screens. I you right click on the Tcad icon, and go to properties, under the "compatibility" tab select "Override high DPI scaling behavior, scaling performed by:" and set the System (Ehanced) as having control. This will apply the system scaling to the application (and in my case does a 2x on all of the pixels) which means that I don't get the benefit of a high dpi screen but at least it is usable for now. I expect this will continue to work until IMSI gets scaling done in the UI toolkit for the application.