Bug 125011 [Contributions] ActionContributionItem should use text for tooltip in toolitems
If an action is added to a toolbar, and it has a name, but no tooltip set, the name should be used as the tooltip (except when the text is actually displayed on the toolitem using setText()) Clients sometimes forget to set the tooltip text when no specific tooltip message exists.
bundles/org.eclipse.jface/src/org/eclipse/jface/action/ActionContributionItem.java
protected boolean isEnabledAllowed() {
        if (getParent() == null)
            return true;
        Boolean value = getParent().getOverrides().getEnabled(this);
        return (value == null) ? true : value.booleanValue();
    }
    /**
     * The <code>ActionContributionItem</code> implementation of this 
     * <code>ContributionItem</code> method extends the super implementation
     * by also checking whether the command corresponding to this action is active.
     */
    public boolean isVisible() {
        return super.isVisible() && isCommandActive();
    }
    /**
     * Sets the presentation mode, which is the bitwise-or of the 
     * <code>MODE_*</code> constants.
     * 
     * @param mode the presentation mode settings
     * 
     * @since 3.0
     */
    public void setMode(int mode) {
        this.mode = mode;
        update();
    }
    /**
     * The action item implementation of this <code>IContributionItem</code>
     * method calls <code>update(null)</code>.
     */