If we have a single digit page number displayed, then we can't use backspace key for removing the page number to enter a new one. There cannot be a state where we have an empty page number box.
#4,594 opened on 2015年10月29日
説明
The major problem here is that suppose we are at page 32 and we press backspace, then '2' is removed from '32' and page 3 is displayed. Now if we again press backspace then we are navigated to page '1' and '1' is displayed in the page number box. Now if we want to see page '9' then we will have to select '1' present in the page number box using shift key or using mouse and replace it with '9'. Backspace key is non-active here. Ideal way should be that if we press backspace then the page should not change and the page number box should become empty so that user can type any other page number.
Current functioning:

Expected functioning:

I have made the solution for it and will be submitting the pull request soon. Please review the issue.