In calc page preview when you keep zooming in to the page such that a part of the page get obscured, both of the right and bottom scroll bars start moving away from the edge of the window frame toward the document, eventually they will even disappear. Resizing the window will correct it.
Noel Power committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/core/commit/?id=05409d2f950cb8c747afa621c0f43e3bafbc56b7 fix incredible shrinking scrollbars when zooming in calc preview fdo#50722
Noel Power committed a patch related to this issue. It has been pushed to "libreoffice-3-6": http://cgit.freedesktop.org/libreoffice/core/commit/?id=daf35c9aa78aad9638e49d81af020677273250d4&g=libreoffice-3-6 fix incredible shrinking scrollbars when zooming in calc preview fdo#50722 It will be available in LibreOffice 3.6.0.