You can re-size panes by dragging on the divider bars between them. To indicate this possibility, the mouse cursor changes shape when hovering over the divider bars.

In addition you will see there are two small left pointing arrows within the vertical divider bars, one at the top of the vertical divider bar between explorer and editing pane and one at the top of the vertical divider bar between to-do pane and details pane. Button 1 click on the first of these will expand the editing pane to the full width of the window, button 1 click on the second will expand the details pane to the full width of the window.

There is also a small downward pointing arrow within the horizontal divider bar at its leftmost end. Clicking on this will expand the explorer and editing panes to the full depth of the window.

By using both the top arrow on the vertical divider and the arrow on the horizontal divider, it is possible to expand the editing pane to use the entire window.

The original configuration can be restored by clicking again on these arrows, which are now located at the edge of the window.