Description Sebastien Arod 2013-06-18 06:22:02 EDT

Reproducible cases:
* Open to the demo application with fancy theme (http://rap.eclipsesource.com/workbenchdemo/fancy)
* Open File>Import dialog.
* The font size of the wizard message is 12px;
* Open to the demo application with default theme in a new tab (http://rap.eclipsesource.com/workbenchdemo/workbench)
* Open the Import Dialog
=> Workbench Theme uses the fancy dialog fonts. This is WRONG


* Refresh the tab using the default theme. 
* Reopen the import dialog. Fonts are back to default theme fonts. (size is 14px).
* Refresh the tab using the fancy theme. 
* Reopen the import dialog. 
=> Fancy Theme uses default theme fonts... !!!


After debugging I found that the problem comes from the fact that ThemeElementHelper.installFont tries to find the font to use from PrefUtil.getInternalPreferenceStore() and fallback to fonts from JFace FontRegistry and then store the result in the PrefUtil.getInternalPreferenceStore().

And since PrefUtil.getInternalPreferenceStore() is of scope session you end up sharing this between UISessions.

Having the same user using multiple tabs with different themes can be seen as a corner case however in our case we have 2 workbench applications each with it's own theme and it's own set of perspective so it would be a frequent use case for us to have the same Session having to deal with 2 themes.


I currently worked around this by adding the following code in org.eclipse.equinox.app.IApplication.start(IApplicationContext) before workbench startup to make sure theme fonts are used by workbench theme:

<code>
// Try to avoid font leaking see Bug #923					
FontDefinition[] fontDefinitions = WorkbenchPlugin.getDefault()
	                .getThemeRegistry().getFonts();
FontRegistry jfaceFontRegistry = JFaceResources.getFontRegistry();        
for (FontDefinition fontDefinition : fontDefinitions) {
       	PreferenceConverter.setDefault(PrefUtil.getInternalPreferenceStore(), fontDefinition.getId(), jfaceFontRegistry.getFontData(fontDefinition.getId()));
}
</code>