Text clipped by filters

I am using an INPUT textfield with filters applied.
Using Palatino Linotype, bold and italic.

If the lowercase letter ‘g’ is the first character in the textfield the descender is clipped on the left side. If the letter ‘f’ is the last character in the textfield the right side is clipped.
The clipping does not appear to be caused by the edge of the textfield, since this can be made visible using
textfield.border = true;
The same effect can be created by removing the filters and setting
textfield.cacheAsBitmap = true;
The cause seems to be the way the italic letters extend outside the ‘frame’ of the character (some letters in Arial italic suffer the same way).
What is Flash doing when it creates the bitmap?
Any thoughts for workarounds?