Not sure if I can explain it clearly, trying my best... The zoom-in behavior of default UI is like Google Maps.

- Let's say the center of the map is a crossway, coordinate (0, 0), When I mouseover a building at (10, 20), and zoom-in 2x, Google Maps will "focus" on the cursor and try to let the building stay at where it was, i.e. (10, 20), and zoom-in everything else. Therefore the coordinate of the origin crossway will become (-10,-20).
+ Let's say the center of the map is a crossway, coordinate (0, 0), When I mouseover a building at (10, 20), and zoom-in 2x (for example), the map UI will "focus" on the cursor and try to keep the building staying at where it was, i.e. (10, 20), and zoom-in everything else. Therefore the coordinate of the origin crossway will become (-10,-20).
- When the map scale is 100%, it works properly; when scale is less or more than 100%, it doesn't.
+ With Mapster, when the map scale is 100%, it works properly; when scale is less or more than 100%, it doesn't. In other words, what under the cursor (the center point of zoom-in) will shift away and not under the cursor anymore.
  What version of the product are you using?
  1.6.2

  What is the expected output? What do you see instead?

  Not sure if I can explain it clearly, trying my best... The zoom-in behavior of default UI is like Google Maps.
+
  Let's say the center of the map is a crossway, coordinate (0, 0), When I mouseover a building at (10, 20), and zoom-in 2x, Google Maps will "focus" on the cursor and try to let the building stay at where it was, i.e. (10, 20), and zoom-in everything else. Therefore the coordinate of the origin crossway will become (-10,-20).

  When the map scale is 100%, it works properly; when scale is less or more than 100%, it doesn't.