Timing of page switching when dragging scroll thumb (or scroll box) on vertical scrollbar in non-continuous mode

[rakunavi]

Hello all,

In PDF-XChange Editor, the timing of page switching when dragging the scroll thumb (or scroll box) on the vertical scrollbar in non-continuous mode seems a bit odd.

For example, imagine that a sample file consisting of two pages is displayed in non-continuous mode with a single page. The zoom factor is set to Page Fit. The following verification video shows the behavior of PDF-XChange Editor on the left and Acrobat Reader on the right.

• sample.pdf

In the video, for each application, you simply observe when the page switches between page 1 and page 2 while grabbing and dragging the scroll thumb.

• Animation.gif
  The capture software used (ScreenToGif) displays a yellow circle around the mouse cursor when the left mouse button is clicked.

If the position of the scroll thumb on the vertical scrollbar is expressed from top to bottom as 0 to 100, the PDF-XChange Editor will finally switch to page 2 only when you drag the scroll thumb to the 100 position, i.e., the bottom-most position. If you release the mouse button at any other position, i.e., 0 to 99, the first page will be displayed.

In Acrobat, on the other hand, the first and second pages switch at approximately the middle position, such as 50 or 51. Releasing the mouse button at the top half of the scrollbar, from 0 to 50, displays the first page, while releasing the mouse button at the bottom half of the scrollbar, from 51 to 100, displays the second page. Most users will probably be more comfortable with Acrobat's behavior, but what do you think?

Note that the points made here also apply to the preview display in the Edit Action dialog.

• Animation2.gif

The following topic also reports on the behavior of vertical scrollbars in non-continuous mode, which may be related to this case.

• Odd behavior of vertical scrollbars in documents with different page heights
  viewtopic.php?t=45770

Thank you for taking the time to read this message.

Best regards,
rakunavi

- PDF-XChange Editor PRO Version: 10.6.0 build 396
- Adobe Acrobat Reader Continuous Release Version 2025.001.20474
- OS Version: Windows 11 Pro / Home 24H2 Build 26100.4061
- PC Model: GMKtec Nucbox M7 Pro with HUION Kamvas Pro 19 / Lenovo IdeaPad C340-15IWL

[Daniel - PDF-XChange]

Hello, rakunavi

Thank you for the report, I have passed this along to the team for review.

RT#7505: Bug: Scrollbar page position normalization

Kind regards,