Users are able to type invalid values on textboxes

[BrianLima]

Users can type non hexadecimal values on the color hex code or type letters freely on R, G or B textboxes.

[zubetto]

Incorrect input is filtered out by the InputComponent and the ColorCodeParser methods.
I tried both your handlers and they still need the above filters because user can input exceeded value or paste arbitrary text from a clipboard. TextBoxPreviewTextInput allows to input digits only but it does not check if the input value exceeds 255. ColorCode_PreviewTextInput does not seem to work properly, I can type arbitrary characters.
It would be nice to verify user input by few lines of code, though!