What can be done with the various window panels within GUI Designer?

The various window panels within GUI Designer can indeed be rearranged and repositioned, allowing users to customize their workspace according to their preferences and workflow requirements. This flexibility is essential for optimizing the design environment, particularly in complex projects where different tools and panels may need to be more accessible based on the user's tasks. By dragging and dropping panels to new locations or resizing them, users can create an efficient and organized workspace that suits their individual project needs.

This capability enhances productivity because it allows users to prioritize certain tools or features and access them quickly without being constrained by a fixed layout. Additionally, such customization can help in managing multiple projects or elements on the interface simultaneously, facilitating a smoother and more intuitive design experience. This makes option C the appropriate answer.