Why Does Internet Explorer Need the "Haslayout" Flag

What is haslayout?

It's a non-standard property on an HTML element which is only supported by IE7 and lower ( IE8 compatability mode too ), which if triggered, causes the element to be rendered in a certain way ( which can be unexpected, random, can be a godsend or can be hell ).

Classic example is giving layout to an element so it can clear floats.

#wrapper { zoom:1; }

The element will now contain floats. Any of these properties and value other than auto/normal will trigger the layout property.

* display: inline-block
* height: (any value except auto)
* float: (left or right)
* position: absolute
* width: (any value except auto)
* writing-mode: tb-rl
* zoom: (any value except normal)

Please have a thorough read @ http://reference.sitepoint.com/css/haslayout

Why can't I launch a web page in Internet Explorer from another browser?

Allowing websites to access PC data and invoke programs would be a major security risk.

The HTML standards define how web browsers should behave when presented with standard markup. Executing a program on your computer (in this case, Internet Explorer) is clearly not a function of a web browser and the means of doing so is thus not defined via HTML.

You may be able to accomplish what you're looking for by writing/installing some add-ins or plug-ins to Chrome/Firefox, augmenting the standard functionality of those web browsers. Just note that if you go that route, you'd be potentially creating a security vulnerability.

Does an Internet Explorer Extension / Add-On run in the same process than IE?

http://blogs.msdn.com/b/ie/archive/2008/03/11/ie8-and-loosely-coupled-ie-lcie.aspx

If in older IE versions, the answer is yes. For IE 8 and above, the answer is usually no.

IE CSS3 box-shadow with dynamic height

Not sure why, but apparently it often helps if you add

zoom:1;

to the div's css.

http://jsfiddle.net/wXNRc/2/

(example is IE-only)

How to test MSN Explorer?

What is MSN Explorer based on?

From the install page here, there is this note at the bottom:

Note: this version of MSN contains Internet Explorer 5.5

Hopefully that helps. I can't use MSN explorer either, so there is no guarantee that this information is correct.

Edit: The IE 5.5 information is corroborated by the warning I got when
trying to access this site from Linux:
http://explorer.msn.com/langwarn.htm?prompt=1

Is there any way to test it?

Based on the info above, if you can find a screenshot site that supports IE 5.5, I would imagine the rendering should match MSN explorer.

Is there any possibility it's just different enough from IE7 to have its own bugs, or should I look elsewhere?

Oh, it's incredibly possible. If you can't get a version of IE 5.5, at the very least, I would suggest grabbing a copy of IE 6. Microsoft supports Virtual PC images that come installed with IE 6 that you could use to test.

IE or Firefox,which one has a more logical CSS handling?

You must be new to web design. Otherwise you wouldn't be calling IE the more humane browser. :)

I see your point but I don't agree with your conclusion. The difference in the box model you are referring to is the only instance where IE's approach actually makes more sense than the official standard. Otherwise, IE usually is the culprit introducing behaviour that drives you crazy.

Browsers have their differences. In rendering, Firefox is generally closer to what is the official W3C standard than IE. IE 8 is the first step towards true standards compatibility on a very wide level.

You will usually need to support every major browser, down to IE 7 or even IE 6. Don't make the mistake of ignoring either, you can't afford it. (Except maybe for IE 6 - it's a discussion in itself.)

A very valuable guide to the differences are the compatibility tables at quirksmode.

Invaluable tools to figure out rendering oddities are Firebug in Firefox, and the new developer toolbar in IE 8. Be sure to have them under your belt when you start working.