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tree menu crashes
johnj108 - 12/5/2003 at 01:57 PM

I notice that using the demo tree menu eventually the system crashes and icons start to disappear when you mouse over them. This is also happening in a development site we are building. Is there any soloution or way to avoid this?

PinkFloydEchoes - 1/5/2004 at 08:32 PM

I am getting the same behavior. The icons disappear, and on some computers it hangs if you click around too much. Is there any way to fix this??

tigra - 1/7/2004 at 05:27 AM

Sometimes we find this behavior when browser has 'Every Visit to the page' caching settings which isn't actually good choice for reasons of high time and network traffic consumption.

Now why that happens: Tree Menu has rollover effect for icons so when you move your mouse icons change. Even if you don't see them change images are actually switched from one to the same (this is something that we'll improve). Script has code that preloads those images so they are waiting in the memory for browser to call them. With that 'Each visit to the page' settings browser ignore what's loaded and sends request to the server for each image. Those multiple randomly generated requests on mouseover and mouseout just kill the browser so some images don't get loaded in time, sometime browser just hungs up. And sad part is that we can't do much about this. The good news is that very few visitors use this caching setting.

The reasons why people use this setting are:
- they are not sure what this means but they hate windows and its automatic settings
- webmasters use it to ensure they get updated content after some files have been reuploaded. this is the good reason, but
1) you can click reload with shift pressed and this will reload all files no matter if they are outdated or not
2) creating web application make sure you use expiration HTTP header. This will give the browser idea how long page (or other resource) stays up-to date. If you set -1d (expired yesterday) then browser will reload it each time (GUARANTEED).

kozman - 1/8/2004 at 07:27 PM

The crash you are refering to is the result of the IE browser not understanding any HTTP packets slated for the current domain. If you go to a different site on another domain and then come back, the tree control will start to work again.

This is a problem in speed of HTTP responses versus requests the browser makes with the web server.

Microsoft KBA article 818506 addresses this issue and they also provide a hot fix.

If your situation is like mine, you can't simply force your customer base (ours is 1 million +) to change their cache setting. With this hot fix, at least there is a mechanism to push out something so that your users aren't dead in the water.

NOTE: The hot fix only solves the inability to continue sending requests against the current domain (the perceived IE crash). You will still see images disappear for the same reasons as described by the SoftComplex moderator, however, the tree will still continue to work.

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