R = getannotrectcoord(H) returns the coordinates R = [X0 Y0 X1 Y1] of 
the annotation rectangle H using the units of the current axis. An 
annotation rectangle may be created either using the menu Insert > 
Rectangle, or using Matlab's annotation('rectangle',[  ]) function. 
 
R = getannotrectcoord, without input argument, uses the active 
annotation rectangle. 
Published output in the Help browser 
   showdemo getannotrectcoord