This member cannot be used in scripts, but is usable in the command bar and plugins.
GetRelativeMousePosition returns the position of the mouse relative to the top-left corner of the
PluginGui. The returned value changes only if a mouse input began on the PluginGui, or if the mouse is presently hovering over the window.
The animation above displays the value returned by this function (the left mouse button is pressed in the animation). Notice how the X-value is negative when the mouse is on the left of the window.
The screen position of the mouse relative to the PluginGui in pixels