PropertyCompatibilityHelpResolver.java parse the .properties files in:
and then sets the appropriate browser icon (Safari, Chrome, Firefox etc.) as active (colourful) or inactive (greyscale) in the Code Completion help depending on whether or not the CSS property is found in each browsers .property file.
The problems are:
1) These .properties files haven't been updated for a very long time, so several properties show as not supported by browsers which have now supported them for ages.
2) Unlike the old days, browsers are pretty quick to implement support, so a straight forward supported/not-supported is not so useful now. It would be more useful to show which version of a browser support for a CSS feature was implemented
3) These .properties files are also used to create browser specific version of CSS properties e.g. -moz or -webkit properties. As these files have not been updated for a long time, Netbeans will not create a lot of browser specific properties that are not available
My proposal is:
1) The properties files need updating with the latest support for each browser
2) Edge needs adding in - this should be a simple case of a new EdgeModule class, icons, properties file
3) The supported version number for each CSS property should be part of the .properties file. The BrowserSpecificDefinitionParser class would need updating to parse the properties file for these version numbers
4) PropertyCompatibilityHelpResolver.java would need updating to create an extra row of HTML in the table containing the browser icons, with the supported version number for the property in
The main thing holding me back is finding a good, reliable source of CSS browser compatibility that is compatible with the Apache licence / not going to cause copyright problems. That seems to rule out MDN etc. and also the web pages for each browser that Netbeans original compatibility information was taken from no longer exist...