Use an offset to draw the Clear button so that it can be better placed based on the...

Use an offset to draw the Clear button so that it can be better placed based on the inputbox right border
For luminos skin use a copy of the Close button and set the proper offset (previously the image itself had the offset)
Add Clear buttons to the other 2 skins (a copy of the Close button for Xaw and the middle part of a checkbox for Default skin, this one not very nice tbh)