Rich text in MS Word legacy form fields?

[jmm]

Hello, I use Word 2010 in Windows 7, and I want my students to fill out text boxes in a protected Word form with a maximum of 3 lines in each box. However, they need to be able to use special characters such as arrows, math symbols, etc. Text boxes from Legacy form fields can have a defined size perfectly appropriate to limit text length to a specified number of lines, but the problem is that they do not allow special characters. Conversely, I understand that Content Control fields allow for rich text, but their limitation only bears on the number of characters, which does not suit my purpose.
To summarize, I am wondering whether there might be a trick to either allow for special characters in legacy text boxes (interestingly, the latter are not wysiwyg as symbols appear OK while working on the form but do not print correctly), or set limits on line number in Content Control fields.
Any workaround or suggestion highly appreciated...

 

[jmm]

Just in case for those interested, there is a simple trick: instead of using form fields, insert 1-cell tables (1 column, 1 line) with a fixed line height and column width. This limits the number of visible/printable lines inside the box, and any character type can be used...