rs.PopupMenu() is supposed to pop up under the cursor position if no optional position argument is supplied.
I have a desktop with two HD (1920 x 1200) monitors (extended desktop), and it works correctly:
However, on my laptop with a 4K screen (225% scaling, 250 is recommended) it is far from correct…
Somehow, this is not being interpreted correctly in this case
screen_point = System.Windows.Forms.Cursor.Position
It may be that the display scaling is causing the problem, but as this is common on 4K screen setups, it does need to work.
You can run this code to test if you like (under a button or from the script editor)
import rhinoscriptsyntax as rs
cl=["egg", "bacon", "sausage", "baked beans", "spam"]
choice=rs.PopupMenu(cl)
This is happening in both V6 and the current V7 Beta (to me anyway)