Better Remmina Resolution under Xubuntu Linux

Remmina, a popular program used to RDP into Windows systems from Xubuntu (and other flavours of) Linux, has a default maximum resolution of 1400x1050. For years I just assumed I was stuck at this maximum resolution until I looked a little closer. It's possible to add your own resolution sizes to Remmina, and it's as simple as a few mouse and keyboard clicks.