text string to measure
output buffer to put measured widths (widthsi will be set to cumulative widths text[0..i])
maximum width to measure - measure is stopping if max width is reached (pass MAX_WIDTH_UNSPECIFIED to measure all characters)
tabulation size, in number of spaces
when string is drawn not from left position, use to move tab stops left/right
TextFlag bit set - to control underline, hotkey label processing, etc...
number of characters measured (may be less than text.length if maxWidth is reached)
Measure text string, return accumulated widths[] (distance to end of n-th character), returns number of measured chars.
Supports Tab character processing and processing of menu item labels like '&File'.