There are two small improvements for UX.

1. When a user exports some of his/her pages, he/she goes into the grid view, selects a few pages, presses "export" and share it, then presses "Done" and "Close" to continue working. It is worth noting that, "Done" is on the top right corner of the window, yet "Close" is on the top left, with "Select" on the right. That means, if he/she doesn't look carefully or press "Done" twice, he/she will again enter the selection mode, rather than quickly returning to work. (See video1). This could be confusing.
   I suggest rearranging the buttons' position so that one can easily export pages and then return working fast.

2. Although there is a button for jumping between pages, when someone wants to go to another page far away, intuitively he/she scrolls up/down fast. When that happens, no assistance is provided -- no scroll bar, no tips, etc.
   I suggest that when the user scrolls fast and goes for over several pages (like 5), the app provides some sort of assistance. For example, currently a small indicator would pop up at the bottom left corner of the page (see video2). It can be used as a button: when user clicks it, a "Go To Page" window shows up.