code: public AT_Context setFrameTopBottomMargin(int frameTop, int frameBottom){
  		if(frameTop>-1 && frameBottom>-1){
  			this.frameTopMargin = frameTop;
  			this.frameBottomMargin = frameBottom;
  		}
  		return this;
  	}
docs: Sets the top and bottom frame margin.
  @param frameTop margin
  @param frameBottom margin
  @return this to allow chaining