@Override
	public boolean performCancel() {
		super.performCancel();
		previousEnabledString = null;
		previousPortString = null;
		return true;
	}
This class represents a preference page that is contributed to the Preferences dialog. By
subclassing {@link FieldEditorPreferencePage}, we can use the field support built into JFace
that allows us to create a page that is small and knows how to save, restore and apply itself.
<p>
This page is used to modify preferences only. They are stored in the preference store that
belongs to the main plug-in class. That way, preferences can be accessed directly via the
preference store.
GhidraBuild/EclipsePlugins/GhidraDev/GhidraDevPlugin/src/main/java/ghidradev/ghidrasymbollookup/preferences/GhidraSymbolLookupPreferencePage.java