Problem styling QScrollBar::handle

I'm trying to customize a scroll bar's appearance by changing its stylesheet and I've been able to achieve nearly everything I want to do except for changing the 'handle' sub-control. If I do anything with the handle, something ends up working incorrectly elsewhere in the scroll bar. For example, if I simply add this to the bottom of my stylesheet:

Code:

---

QScrollBar::handle {
   background: rgb(255,255,255);
}

---

the resulting scroll bar has a white handle but it allows the handle to be dragged over the full extent of the scroll bar control, including over the add-line and sub-line controls! Other changes cause other strange behaviors, such as the add-line and sub-line controls being fully obscured by the add-page and sub-page areas, etc.

Here is my stylesheet in its current state; it works exactly as I want except for the handle styling:

Code:

---

QScrollBar:vertical {
	background: rgb(64, 64, 64);
	min-height: 50px;
	width: 50px;
}
 
 
QScrollBar::sub-line {
	border: 1px solid white;
	image: url(:/Common/arrow_triangle_bright_up.png);
}
QScrollBar::sub-line:pressed {
	image: url(:/Common/arrow_triangle_black_up.png);
	background: rgb(255,255,255);
}
 
QScrollBar::add-line {
	border: 1px solid white;
	image: url(:/Common/arrow_triangle_bright_down.png);
}
 
QScrollBar::add-line:pressed {
	image: url(:/Common/arrow_triangle_black_down.png);
	background: rgb(255,255,255);
}
 
QScrollBar::add-page:enabled, QScrollBar::sub-page:enabled  {
    background: none;
}

---

Is there something wrong with my stylesheet and it just happens to work if I don't mess with handle styles?

I'm doing this in Qt 4.5.0 (yeah, I know this is a fairly old version) under Win7/MSVC2005 (also kind of long in the tooth).
Has anyone encountered this problem? If so, how did you resolve it?

Thanks!