Question

I have a WinForms control inherited from TreeView and I want it to automatically adjust background color according to the form (also customized) background. How to make it?

Answer 1

Making a control aware of its parent is normally a bad idea. There however is a dedicated method to detect the parent BackColor changing so it’s okay. BackColor is an ambient property, if it isn’t explicitly assigned then has the same value as the parent’s BackColor. So take advantage of that:

using System;
using System.Windows.Forms;

class MyTreeView : TreeView {
    protected override void OnParentChanged(EventArgs e) {
        if (this.Parent != null) this.BackColor = this.Parent.BackColor;
        base.OnParentChanged(e);
    }
    protected override void OnParentBackColorChanged(EventArgs e) {
        this.BackColor = this.Parent.BackColor;
        base.OnParentBackColorChanged(e);
    }
}