Fixed #252 adds the arrow to the tooltip window at the cursor location

Without the ```x.ShowTooltipWindow``` override the arrow doesn't know where to show.  

Also removed the use of ```Region.EndColumn``` for the calculation of ```segment``` as we never set EndRegion, it is always -1.  

We now use a segment that is 1 column wide, which is the same as it currently works, ideally we should set the segment to the size of the ident we are hovering over but there is no code to calculate that yet.