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    <p>As hyde said, you really would need to separate your behaviour from what your classes <em>are</em>. You said you didn't want to use interfaces; well, I can't think of a way around that. You may have to bite the bullet or do some code duplication.</p> <p>At minimal, you can move the behaviour logic to a separate controlling class and simply feed it some interface that exposes the members needed. Consider the few properties you <em>need</em> for a scrollable UI control (mind you, this is all just whipped off examples, I doubt these types exist as I describe, or these are the actual <em>minimum</em> set needed): </p> <pre><code>public interface ISCrollable { Control Target { get; } ScrollBar Bar { get; } double FullLength { get; } double VisibleLength { get; } } </code></pre> <p>You then can put your scrolling behaviour in a class that attaches that behaviour or works upon an <code>IScrollable</code>:</p> <pre><code>public class Scroller { public Scroller(ISCrollable scrollable) { //attach behaviour scrollable.Bar.OnClick += DoScroll; //and other stuff } } </code></pre> <p>Finally, your <code>ScrollableWidget</code> would be your <code>Control</code> and attach the scrolling behaviour rather than inheriting it:</p> <pre><code>public class ScrollableWidget : Control, INamingContainer, ISCrollable, IWidget { private Scroller ScrollBehaviour; private Widgeter = WidgetBehaviour; public Control Target { get; private set; } public ScrollBar Bar { get; private set; } public double FullLength { get; private set; } public double VisibleLength { get; private set; } public ScrollableWidget() { this.Target = this; this.Bar = CreateScrollBarControl(); this.FullLength = 9001; this.VisibleLength = this.ActualHeight; this.ScrollBehaviour = new Scroller(this); this.WidgetBehaviour = new Widgeter(this); } } </code></pre> <p>So yeah, you're going to want to use interfaces. I don't understand your requirement not to. There are other patterns, such as <a href="http://en.wikipedia.org/wiki/Decorator_pattern" rel="nofollow">Decorator</a>, that may be a better suit than the mess I just posted.</p>
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    1. POI need to inherit from two classes (which is impossible in C#) can anyone recommend a different way of doing this?
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    1. COThanks for the code, I've nothing against interfaces. What I was saying is that both classes declare bodies of code so couldn't be contained in just an interface. However using a class and an interface (IScrollable and Scroller in your example) makes sense, thanks.
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    2. CO@JoeNFU Yeah, so try moving the _logic/implementation_ of those classes to a separate controller that isn't dependent on the class hierarchy and instead just _attaches_ behaviour to any `IScrollable` provided to it.
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    3. COThats fixed it, thanks. Going to go read a book on design patterns now.
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