There are quite a few questions here on SO about the following meta tag not being HTML5 compliant and therefore will not validate when using <!DOCTYPE html>:
<meta http-equiv="imagetoolbar" content="no">
I also know this tag is specifically for one purpose alone: hiding the toolbar that appears when you hover your mouse over any image in Internet Explorer.
However, I could not find out in exactly which versions of Explorer this is applicable. When I Googled it, most results only mention IE6, but these threads/pages were posted back in 2004. I'm wondering if that's because the feature was dropped in IE7+.
I do not care about IE6, but if this meta tag is applicable to IE7, IE8, IE9, etc. I'll need to decide if I want to find an alternative method.
Exactly which versions of Internet Explorer enable the annoying Image Toolbar feature that is disabled via the meta tag above?
Apparently, the Image Toolbar was only a feature in IE6. It was replaced with the contextual menu (right-click) in subsequent versions.
IE6 is dead so I won't be concerned about not using this meta tag any longer.
来源：https://stackoverflow.com/questions/7207649/imagetoolbar-meta-tag-and-ie-versions