The x property defines the x coordinate of the Widget.
If the positioning property is set to TOP_LEFT, CENTER_LEFT or BOTTOM_LEFT, the x-coordinate is the distance of the Widget's left edge to the left border of the screen.
If the positioning property is set to TOP_CENTER, CENTER_CENTER or BOTTOM_CENTER, the x-coordinate is the distance of the Widget's horizontal center to the screen's horizontal center.
If the positioning property is set to TOP_RIGHT, CENTER_RIGHT or BOTTOM_RIGHT, the x-coordinate is the distance of the Widget's right edge to the right border of the screen.
The x property can be given in absolute pixels or in percent. +100% don't mean the total screen width, but total screen height * 4 / 3 to avoid scaling problems between 4:3er and 16:10er resolutions. Use the opposite positioning to achieve this. The editor will do this automatically when dragging with the mouse. Hence the value could have these forms:
Click the "px" or "%" button to convert between pixels and percent (preserving the absolute value).