Questions about XULElement attributes, properties, styles

[Wang Xianzhu]

The relationships among XULElement's attributes, properties, and its 
style's attributes and properties make me confused.

For example:
<vbox id="vbox1" height="20" style="max-height: 40px"/>
In JavaScript Debugger:
var vbox1 = document.getElementById("vbox1");
var vbox1style = document.defaultView.getComputedStyle(vbox1, "");
vbox1.height;  			/* result is 20 */
vbox1.maxHeight; 		/* result is "" */	<== NOTE A
vbox1style.maxHeight; 		/* result is "30px" */
vbox1style.height;		/* result is "20px" */
vbox1.maxHeight = 50;
vbox1.style.height;		/* exception: NS_ERROR_NOT_IMPLEMENTED 
[nsIDOMXULElement.style] */				<== NOTE B
vbox1.height = 100;
vbox1.height;			/* result is 100 */	<== NOTE C
vbox1style.height;		/* result is "50px" */	<== NOTE D
vbox1style.maxHeight;		/* result is "30px" */	<== NOTE E

Questions:
1. I know that element properties are linked to attributes in XBL or 
some other scripts/programs. However, why not make a single view of 
element attributes and element's style attributes (NOTE A) ?  When I use 
XULElement.height, I expect to get the actual height of the element 
(i.e. 50, not 100 in NOTE  C)

2. Why XULElement.style not implemented?  I think that linking 
XULElement.style to document.defaultView.getComputedStyle(XULElement 
ele) is simple implementation. (NOTE B)

3. Assigning to XULElement's properties or attributes makes recomputing 
of styles, but I'm confused why vbox1Style.maxHeight (style's 
"max-height" attribute) does not reflect its actual value (50px, not 
30px in NOTE D), while vbox1Style.height does (NOTE E).

Regards,
Wang Xianzhu