If there are AutoSizeRows = true and TextBox column with Multiline=true then puting the column in edit mode is impossible. 

Please note that this worked with Q2 2009 SP1, but there are two glitches:
- in the first edit, the grid's row loses its heigh
- In edit mode if arrow up key is used to navigate inside the text when cursor is in second row, next arrow up press brings the cursor to upper cell instead to the first row of the text.