Returns the index of the line that contains the specified
character offset.
@param offset the character offset
@return the line index
@exception IllegalArgumentException <ul>
<li>ERROR_INVALID_ARGUMENT - if the character offset is out of range</li>
</ul>
@exception SWTException <ul>
<li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
</ul>
Returns the index of the line that contains the specified character offset.
@param offset the character offset @return the line index
@exception IllegalArgumentException <ul> <li>ERROR_INVALID_ARGUMENT - if the character offset is out of range</li> </ul> @exception SWTException <ul> <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li> </ul>