TGuiAnimation
 

TGUIAnimation (TGraalVar):
amplitude - float - amplitude for moveupdown, moveleftright and zoominout
currenttime - float
delay - float - the animation starts after the specified number of seconds
duration - float - the animation will last the specified number of seconds
interval - float - interval for moveupdown, moveleftright and zoominout
tabfirstonshow - boolean - calls tabfirst() after showing the control, by default true
timing - string - timing function: 'linear' or 'sinus', sinus is only used for moveupdown, moveleftright and zoominout
transition - string - specifies the animation type: fadeout, fadein, moveoutleft, moveinleft, moveoutright, moveinright, moveouttop, moveintop, moveoutbottom, moveinbottom, moveupdown, moveleftright, flipoutleft, flipinleft, flipoutright, flipinright, zoomin, zoomout, zoominout, growin, growout, shrinkin, shrinkout, rotateoutleft, rotateinleft, rotateoutright, rotateinright

Was messing around with this a bit last night and discovered a few things about this, if stopanimation is called during/after an animation, the GUIObject returns to its original spot.

It also seems there is no way to not use the moving to stop short of the width/height of the GuiControl that is moving so more complex motions aren't possible (IE, collapsing downward, then sliding out to the right).

Is it possible to have transitions and additional variables added (IE a delta value for the transitions) so that

would move the GUI 50 pixels to the right

The createAnimation() isn't exactly changing the position of the control, the only variable that is persistenly changed is the visibility. Everything else is just a transition, temporary modification of the values.
You can however combine some animations, especially with the moveupdown and moveleftright animations, e.g. doing a half interval with having interval half of the duration.