Progress Telerik UI for WinForms
RadSplitContainer provides interactive splitters and split buttons. This feature allows the end-user to more intuitively collapse or expand a panel when needed. Thanks to this out-of-the-box feature, you no longer need to use code to control the expand/collapse behavior of your end-users.
The SplitContainer Designer gives you full interactive design-time control over the containers, position, and properties of splitters within the SplitContainer. You can visually design the initial size and position of the containers and splitters on your form without writing a single line of code. The component also comes with the most common options included directly in the smart tag:
Contrary to the standard SplitContainer control, Telerik Windows Forms SplitContainer can be skinned to your liking. In addition, it is shipped with a rich set of themes that allow you to easily build slick interfaces with the look-and-feel of Windows 8, Office 2010, Office 2013, Metro, etc. The themes can be easily switched using a single property.