You can set a limit on how much the field can grow but you can't set a limit on the number of lines of text that can be inputted.
Here are a few options:
1) Have the field not be dynamic and set it to Limit to Length to Visible Area
2) Same as above except if you want it dynamic, the user could enter into the field, it would grow to show how much the user can input, and if they input less it would shrink down when they exit the field. (some coding needed)
3) Use a mono-spaced font like courier and count how many characters it takes to produce 5 lines. Then set the maximum character length based on that.
4) If using a different font, determine each letters width and use script to add up all widths to determine number of lines (half joking on that one)
Kyle
