About highlighting feature on the pre-release version


First of all, I want to give huge thanks to the Sumatra PDF team; it is lightweight yet has almost all the functions needed, and it has been a pleasure using this program.

I wanted to give some feedback about the highlighting feature provided in the pre-release version:

  1. The highlighting works fine in most cases, but I wish I could undo highlighting more easily; highlighting on the same line can be sometimes buggy, confusing and time consuming. Making ‘ctrl+z’ for undoing and ‘ctrl+y’ for redoing would be awesome[Edited: I forgot that highlighting can be undone by reapplying it].

  2. I’m personally fine with controlling the color via text file, especially if incorporating a color palette takes too much of computer resources. I still wish though that there was a simple way of alternating between different colors by, say, making about 3~5 rooms for different colors in the text file and then make them selectable through key combinations. This way, we can keep the program lightweight and still enjoy the convenience.

  3. Highlighting texts can be somewhat buggy and bumpy especially when the line consists of some mathematical formulas.
    Quite often, the space under the line gets highlighted as well.
    It is not a huge deal since I can use ‘ctrl+mouse+h’ but still annoying. Also, the end of a hightlight is sometimes either too close to the end of the last word or too far away from it (highlighting the margins after the last word as well).

  4. I wish ‘ctrl+s’ saves the changes on the same document rather than trying to save the file into a different place.

I’m still using Sumatra PDF since its concise set of features is unbeatable. I really wish that the highlighting feature will soon be on the release version with some inconveniences fixed since highlighting is just so darn useful!


I’m just a user (not developer) so comments are not the official line

There are 2 highlight modes (save into document = true or false)

My preference is “false” as it allows more control, however the downside is a secondary filename.smx thus only a SumataPDF recipient getting both files would see the highlight

The alternative of “true” makes permanent changes to the source PDF which means I would first keep a “clean” copy, thus it also results in 2 files, but I can send the highlighted copy to users with other PDF readers and expect (hope) they see them

addressing your comments

  1. it is a bit buggy (hence not in the release version), KJK as the main developer usually has higher demands to improve the reading aspects of SumatraPDF and annotation / editing is not a priority

  2. see 1 above, the smx file can be edited in notepad etc. e.g. to change highlight to underline

  3. The selection of text is not wholly dependant on SumatraPDF rather it is an issue as to what OCR’d the source document so if it removed spaces or added them or replaced symbols / fonts with gigbberish you cant blame Sumatra for being mislead as to where the characters are. However with the smx file you can tweak the size of the highlighted area as you wish

  4. see the comment above about using save into file = “true” thus best to save as a different name to indicate it is modified


Sorry forgot to include the link to a great little add-on that may be of use see



Thanks for your reply! I’m also using ‘save into document=false’. I just wish ‘ctrl+z,y’ was implemented; not only it is convenient, it will undo the highlighted area created by ‘ctrl+mouse+h’.

I also like the fact that the team is focusing on the reading aspects. That is why I prefer Sumatra PDF in the first hand. But I think adding a couple more lines in the text file for easier control of the color can be definitely helpful yet not tremendously difficult.

The buggy aspect of the highlighting feature is probably dependent on the OCR, but other PDF programs don’t have the bugs, so I was hoping those will be fixed in the near future. I can take those bugs for now, though.

I tried the Sumatra highlight helper a few weeks ago, but it was buggy and didn’t operate correctly for some reason.

[Edited] I found that when there is a space after a word, Sumatra PDF highlights the space after the word as well, so (hey) gets highlighted correctly but (hey you) gets highlighted including the space after ‘hey’.