I'm attempting to reproduce some legacy C++ MFC UI controls. One feature is the ability for the User to type in either a double value, or, a mathematical expression like "1 + 200mm - 9in". Parsing the expression will be entirely up to my own code. And no, telling the user to use the Calculator drop down isn't going to cut it since the expression can have some pre-defined domain specific variables in it also.
The DoubleEditBox limits input, so using anything but digits, and decimals is prohibited.
Any thoughts on how I might get this functionality to work with any of the Editor Controls?