May I suggest implementing a change timestamp dialog? Similar to the screenshot above from XnView. This will make the XYplorer change timestamp functions more powerful and easier to use by having all functions in one interface.
scrollbar scrolls through all selected pics--i guess to see what you have selected. i dont use the scrollbar though, since you can already see what is selected in the browser.
If you need a change timestamp dialog you can try FileMenu Tools. It adds a folder to the windows context menu with some useful tools which you can use with XYplorer. It automatically installs 32 and 64 bit versions so can see them in 64 bit Windows 7. I only use the timestamp dialog tough.