Scroll bar UX fix

### Old behavior

User scrolls drop down list and when scroll comes to end browser will start to scroll it's main window scroll. This is sometimes really frustrating. Especially when we have drop down lists on dialogs.

It can lead to screwed up dialogs.

### New behavior

Scroll inside drop down list will only work there until mouse is over the list. Scroll of main window will only work when mouse is not over the drop down list.