The new beta can be downloaded from here.
There are two news in this beta 5. First I improved borderline handling in tables and matrices. When you insert new rows/columns the borderlines of matrix cells should now behave in a more predictive way. This required some deeper changes in underlying data structures so please let me know if you find a bug when working with tables/matrices.
Secondly, I tried to refine handling of cursor movement when using keyboard arrow keys. It is quite difficult to implement a predictable cursor movements within irregular structure of a math expression. The most important new thing is that if you hit the opposite arrow direction key than in the very previous stroke, the cursor will return back to where it originally was. I hope this will help when correcting unwanted cursor moves.
In addition, pressing the left or right arrow key will always put the cursor into the fraction numerator (or denominator) – until now the cursor would jump over the fraction if the fraction was quite short. Plus, when moving cursor through multi-line text field it will move in a way more similar to standard text processor.