Is there visual focus during a saccade? Has anyone succeeded in measuring where the focus is between saccades? Through some kind of nonintrusive brainscan perhaps? I would like to be able to draw with my thought :) (Something similar would be okay, like the position or shape I am thinking of overlayed on what I see)
Short answer
The retinal image cannot be refocused on an intermediate target during a saccade. 

Background
Psychophysical experiments have shown that during a saccade, attention is aimed at the target location. Instructing the subject to make a saccade from location A to C, while focusing on another point B proved impossible. 

The authors conclude that: 


  [A] saccade executed to a peripheral location in the visual field
  involves the orienting of attention to that location, prior to the
  actual execution of the saccade. The inability to orient attention to
  one location and simultaneously execute a saccade to another location
  suggests that orienting of attention may be an essential component of
  preparing and/or executing saccades.


In other words, a saccade is meant to shift the point of focus, and attention cannot be paid to another point during a saccade.

Reference
- Hoffman &amp; Baskaran, Perception &amp; Psychophysics (1995); 57(6), 787-95