[PHPStorm] How to understand browser icons in content assist?

[midnite]

In the image attached below, in the (3) light blue content assist box, on the left there are 5 Firefox browser icons. What do they mean? Seemingly they mean those methods are only supported in Firefox. But of what versions? And if a certain element is supported in both Firefox and Chrome, but not IE, how will it show (as there is only 1 column space for 1 icon)?

 

 

(image from http://www.jetbrains.com/phpstorm/webhelp/familiarize-yourself-with-phpstorm-editor.html)

 

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On the other hand, in Aptana, there are different columns of browser icons, showing levels of support by light up or not.

 

 

(image from http://aptana.com/products/studio3)

 

In addition, in the description area, detailed browser versions of support is also shown.

 

 

(image from my test of Eclipse + Aptana plugin)

 

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If one asks why dont i just use Aptana, and forget about PHPStorm? As there are some significant drawbacks while coding JS in Aptana, and some says Aptana browser version support is not worth trusting. That's why I am looking for different IDEs.

 

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In conclusion, how to understand browser icons in PHPStorm content assist?