who uses microsoft htc files? and if so for what reasons and how large of a project?

[apl]

i am using and it heavily in an app that is ajax based and there are instances of some htc files not loading on event 'documentready' but others which do load up fine. Any reasons why that might occur?

[jaxicle]

For Microsoft (NSDQ: MSFT) Internet Explorer 5 and later, HTML Components (HTCs) provide a mechanism to implement components in script as Dynamic HTML (DHTML) behaviors. An HTC is an HTML file that contains script and a set of HTC-specific elements that define the component. The component is saved with an .htc extension. This section lists these HTC-specific elements and the members they support.

http://msdn2.microsoft.com/en-us/library/ms531018.aspx

I have only seen .htc files used for the transparency issues that IE5+ has for transparent .png's and if designers/developers want to implement .png's into the design of their site. I've used them sparingly.

It's also used for the :hover selector in CSS, because IE5+ doesn't support it. basically meaning, when you hover over a link and want the link to do something special, you have to code a workaround for IE.

Like so: http://www.xs4all.nl/~peterned/csshover.html

The file is also only usable by Internet Explorer as well.

[sam]

We use HTC files to highlight buttons and entry fields for web applications. For example, when a user tabs from one field to the next, the background color of the input box changes from white to light-blue. When you have several dozens fields on the screen, it allows the user to quickly identify which field has focus without having to search the screen for a small blinking line.

HTC files makes this easy because you can simply add a class="FieldStyle" to the input tag instead of onFocus="this.backgroundColor='#123456;'" onBlur="this.backgroundColor='#654321;'". What's better yet, is that if you have hundreds of fields on multiple pages, you only have to change the color in the HTC file instead of each and every field.

There is a small side effect to this however... IE reloads the HTC file for each and every input that uses it. Since, the file is cached on your local hard drive, this is usually not a huge deal and is very fast. However, if a person has a slow PC and your site is SSL secured and the person has disabled caching for secured sites (which is normal), IE will be VERY slow in rendering the page.