I would like to know if anyone can send me in the right direction on this matter:

I would like to build a form that books out rooms. I would like for a time line to appear with 1/2 hour intervals and be able to click under it and click on start and end time and a vertiacl box will appear. once i have scheduled the event i would like to click on the right side of this new bar and expand the bar to increase the time alloted or make the line shorter. My problem lies in how to create a graphical object that can grow. A status indicator bar is bascially what i am envisioning that can be controlled by the mouse.

Any help would be greatly appreciated. Thanks.