Actually I have found this solution to restore task pane more accidentally than I have clicked away that in libre office impress on Ubuntu 13.10.
Sorry to say, ex_bubblehead, you were a bit wrong. There is nothing to view as task pane in libre office 4.1.3.2. Only slide pane view is available.
If anybody is facing the problems of unable to restoring back the task pane, here is the solution.
(1) Open Libre Office Impress.
(2) Go to Tools>Customize.
(3) Go to Keyboard section, go to functions option.
(4) There go to Category, select View in there. On the right side of Category you will see the list of functions of View. Select task pane in there, modify its shortcut key (E.g. - Ctrl+Alt+0 or Alt+Shift+Right or like that). Please note that you should select that shortcut keys which are disabled for any functions. If you try to modify that shortcut keys which exist any function, then you should lose the default function and modify it with your new function which could create problems later.
(5) Exit from the Customize, press your assigned functional key and you would restore your task pane back.
I have done with Alt+Shift+Right keys to restore my task pane.