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Window Manager
Brian Livingston
CacheSentry's author offers an update on the peculiarities of Internet Explorer 5

MICROSOFT'S Internet Explorer (IE) 5 is now a standard part of Windows 98 Second Edition, Microsoft Office 2000, and other Microsoft products. As an upgrade to Version 4.0, IE 5 is billed as having many improvements -- but it also has its share of anomalies.

Readers have sent me numerous pointers on IE 5. I printed some of these in my April 26, May 10, May 17, and May 24 columns. (See

I asked for a reaction to these comments from David Pochron, author of CacheSentry, a free utility that manages IE's Web cache files more efficiently. I wrote at length about this on March 30, April 6, and April 13, 1998. (See

The IE 5 behavior about which the most readers have written to me involves the Back button. This button, of course, is supposed to return the browser to a previously visited Web page. But numerous readers have reported that after a few minutes of surfing the Web, IE 5's Back button won't go back more than one page. When this happens, the Back button is "grayed out" and fails to function. This gray-out can also affect the Forward button, if you've just gone back.

Pochron says these gray-outs occur because IE 5's Update Frequency is set to Automatic. He suggests changing the Update Frequency to "Every time you start Internet Explorer." This restores the Back button's reliability.

I asked Microsoft to comment on this problem. A Microsoft representative, who asked not to be named, said, "This problem should resolve itself every time you restart the browser without even having to change the setting. This is an issue that Microsoft will address in a future update, though timing is TBD [to be determined]."

Another concern of Pochron's is the display of progressive JPEGs. These graphic files are interlaced -- the image is first displayed at one-quarter of its normal resolution, then one-half, and so on. Web designers use progressive JPEGs to help readers decide whether to wait for the whole image to load or switch instead to another page. If you see the first version of the image and decide you are not on the page you want, you can switch to another page without waiting for the full image to download.

"IE 5 still doesn't support progressive loading of progressive JPEGs, like Netscape has for years," Pochron says. "What IE does when it encounters a progressive JPEG is it waits until the entire image has downloaded before displaying it, which can take several minutes for large images over modems. This completely defeats the purpose of the progressive JPEG and actually makes its display slower than if it had been a regular JPEG."

Pochron also dislikes the fact that, "for some reason, Microsoft disabled the 'alternate image' HTML tag in IE 4.01 and 5 -- it worked in IE 4.0. The alternate image tag allows a Web-page designer to specify and display a black-and-white, lower-resolution version of an image before displaying the slow-loading, full-color, high-res version."

The Microsoft representative's response: "With [progressive JPEGs], Netscape does true rendering, where they will actually put up the blurry image and make numerous passes to get to the clear image. We are not architecturally unable to do this, but customers have not been asking for it, and our priority is to deliver to customers functionality they are requesting."

What about the original reason CacheSentry was created: the need to replace IE's flawed Web-page cache? Pochron was one of the first to find that IE 3.0 and 4.0 "randomly" delete pages from the cache rather than eliminating the oldest pages first.

"Generally," Pochron says, IE 5 now "does remove the older files from the cache." He recently discovered that IE 3.0 and 4.0 delete files based on their default order rather than their age. The default order is similar to the way DOS lists files if you do not define a sort order, and it isn't necessarily chronological.

For those using IE 3.0 or 4.0, you can download the free CacheSentry utility from You may still find some benefits even if you are now using IE 5, as explained on Pochron's Web page.


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