How to override apply and restore defaults - eclipse

Question

I want to configure some appearance settings for a type of file. So I created a new entry in the General->Appearance->Colors and Fonts.
My plugin.xml looks like this:
<extension point="org.eclipse.ui.themes">
<themeElementCategory
id="com.example.themeElementCategory"
label="My specific settings">
<description>
Control the appearance of .example files
</description>
</themeElementCategory>
<colorDefinition
categoryId="com.example.themeElementCategory"
id="com.example.colorDefinition"
label="Some Color"
value="COLOR_DARK_BLUE">
<description>
Your description goes here
</description>
</colorDefinition>
<fontDefinition
categoryId="com.example.themeElementCategory"
id="com.example.fontDefinition"
label="Some Font"
value="Lucida Sans-italic-18">
<description>
Description for this font
</description>
</fontDefinition>
</extension>
Now in the Colors and Fonts I have a new entry were I can set the color and the font.
How can I extend the preferences window so I can override the Restore defaults, Apply and Apply and Close buttons?
In my <themeElementCategory> I will have to add a class=MyHandlingClasswhich would override the performApply(), but what should that class extend/implement?
Same as 1, but add a PropertyChangeEvent, still don't know what should extend/implement
Less likely, create a new preference page which extends the PreferencePage and implements IWorkbenchPreferencePage
How can I achieve one of the first two options?
UPDATE FOR CLARIFICATION
Currently the color and the font for a specific file extension are hardcoded in a class( I KNOW).
When the file is opened in the editor, the informations are read from that static class and visible in the editor.
What I wanted to do:
In a static{} block, read the settings configured in the preferences and update the static fields from my class.
If the user changes those settings from the preferences, on apply I wanted to update the static fields from the class and "repaint" the editor.

Answer 1

If you just want to know when theme items change value use the addPropertyChangeListener method of IThemeManager to add a listener for changes:
IThemeManager manager = PlatformUI.getWorkbench().getThemeManager();
manager.addPropertyChangeListener(listener);
The PropertyChangeEvent passed to the propertyChanged method of IPropertyChangeListener contains the id, old and new value of the changed theme item.