The Tektronix mode is still a bit in a mess. This will change with the using the 4105 command set, this implies that you should only use the vector mode of the 4010 emulation as all other 4010 commands will probably be removed from the program.
Right now scaling is done with respect to a 4010 with 1024*780 points, this probably will change for the 4105 (512*360) emulation. In Tek coordinates the screen measures 4096*3120 points (4105: 4096*3072 points).
For redrawing and zooming purposes the incoming characters are stored in a circular buffer. This is quite a memory saving way to store them6.1, but on the other hand this means they have to be decoded every time the vectors are drawn.