#130 First scroll fails when changing property

[Cameron Martens]

Version: 2.7.1
OS: Windows 7 64-bit

When I try to change a property of a component, and I scroll the list up or down with the mouse wheel, the list disappears.
Note: It only disappears the first time. The second time I try it will work.
To reproduce:
- Add an AND gate to any circuit (any component where you can scroll a list in it's properties will work)
- Select the gate
- Click on the "Data Bits", or the "Number Of Inputs" property
- Move the mouse over the drop-down part of the list
- Try to scroll up or down
The list will disappear the first time, but if you try the exact same steps again, then scrolling will work.