TYPO3 Core

pageTSConfig:

wizardItems.[group].elements.[name].icon is defined as image resource. It is possible to either set it via PHP like here: http://docs.typo3.org/typo3cms/CoreApiReference/ApiOverview/Examples/ContentElementWizard/Index.html with ExtensionManagementUtility::extRelPath or make the path relative with ../../typo3conf/ext/myextension but using EXT:myextension is not working.

Example which should work:

mod.wizards {
    newContentElement.wizardItems {
        special {
            elements {
                worldmap {
                    icon = EXT:contentelements/Resources/Public/Images/worldmap.gif
                    ...
                }
            }
            show = *
        }
    }
}