The Go To dialog allows for precise entry of visible map coordinates. To open the dialog, click the Go To button on the map:

By default, the From and To textboxes contain the map coordinates that are currently visible on the screen; the Range textbox at the bottom contains the same coordinates as a single line of text (which is convenient for copy/pasting), and the slider in the middle displays the currently visible range graphically. To quickly change the visible region, drag one of the circular handles with your mouse:

       

As you drag the mouse, the map in the background will automatically pan and zoom to the new range. You can also enter the starting and ending map coordinates manually, by entering (or pasting) them into the From and To textboxes, or by typing (or pasting) the desired range into the Range textbox. For example, you can enter "1..5000000" to select the first 5Mbp:

As always, click the Close button (or press the Esc key) to close the dialog and return to the map.