How Can I Enable Keyboard Navigation in a Custom Panel Control for Layer Manipulation?

Enabling Keyboard Navigation in a Custom Layer Control Panel

A user encountered issues with keyboard navigation in a custom panel designed for layer manipulation within a graphics application. The panel, derived from the Panel class, wasn't responding to keyboard input or focus events.

The solution involved directly modifying the Panel class to address this:

1. Enabling Focus: The SetStyle method was modified to enable the selectable property, making the control focusable.
2. Focus on Mouse Click: The OnMouseDown event handler was overridden to programmatically set focus to the control when clicked.
3. Handling Cursor Keys: The IsInputKey method was extended to recognize and process up, down, left, and right arrow keys.
4. Focus Rectangle Management: The OnEnter and OnLeave events were overridden to redraw the control's client area, ensuring the focus rectangle appears and disappears correctly.
5. Drawing the Focus Rectangle: The OnPaint event was overridden to draw a visual focus rectangle around the control when it has focus.

These changes ensure the custom panel correctly receives focus and responds to keyboard input, enabling the desired layer navigation functionality. The provided code demonstrates the modified class implementing this behavior.

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