Description Andrey Loskutov 2020-05-20 12:44:11 EDT

We are observing regression from bug 302918.

We have view with CommandContributionItem's contributed to the toolbar.
Some of them are initially disabled.
Before 4.14 we see "disabled" icons on the toolbar, after update to 4.16 we don't see anything but the buttons *are* there, because there is a tooltip while hovering over them.

I've bisected this to bug 302918 changes. 
The problem here is: 

1) CommandContributionItem creates ToolItem without icon in org.eclipse.ui.menus.CommandContributionItem.fill(ToolBar, int)
2) ToolItem.setEnabled(false) is called from CommandContributionItem.updateToolItem()
3) ToolItem.enabled is now false
4) CommandContributionItem.updateIcons() calls now with non-null icon to ToolItem.setImage(Image)
5) ToolItem.enabled is false, disabledImage is null, so the check below is true and we return without setting the image. 

if (!enabled && disabledImage != image) {
	return;
}

The patch would be to additionally check if the disabled image is not null before refusing to set enabled image:

if (!enabled && disabledImage != image && disabledImage != null) {
	return;
}
setImage(image);

I will provide a patch.