But right now this issue has been fixed by Felipe Heidrich.
See the snippet:
Can you see the difference between first and second paragraph? I think it will address many many issues that you had with text indentation.
The most important new API method is:
StyledText#setLineWrapIndent(int, int, int)
The patch was released into Eclipse 3.6 M4 stream, so you need to checkout SWT from HEAD to utilize this awesome functionality.