You can collapse the palette area to allow more screen space for working with the layout and non-layout regions of the UI Design Editor.
NOTE The Palette title bar is still visible when the palette is in its collapsed state. This allows you to access to the Show Palette control.
Figure 1 - The Palette in its 'Show' state
Figure 2 - The Palette in its 'Hide' state
NOTE While the palette is in its hidden state, you may temporarily display and use its contents by pausing the cursor over the palette title bar. The palette will expand to its 'shown' state and display its title bar along its inner edge. When you move the cursor outside of the palette, the palette will retrun to its hidden state.