I found something weird and hope this is the right place to drop a line. I made a grid and a renderer to format one of the columns. The renderer returns a <div style="border: 1px solid red;">val %</div>. Everything is ok as long as you don't lock columns. As soon as you do the height of the rows of the locked columns of the locked part becomes smallers than the unlocked onces. This means the 2 parts of a line, the locked part and the unlocked part start to become unaligned.
Hope thips helps someone. For the time being i just don't lock columns and everything is ok.
Keep up the good work Jack.. and ofcourse all other little helpers.