@bgupta ping?

Given two weeks passed without a comment, I will follow KA release managers' okay to push on own responsibilities now (meh).

If there was a test plan, I could at least try to apply this on my system and verify it works... How exactly the filename should change?

Thanks for the offer, @alexeymin:

Test plans:

Export screenshot image to Gwenview (or other app) via menu:

1. Take screenshot
2. Export Image... > Gwenview
3. Check file name shown in application

Expected:
Matching the filename pattern defined in the settings

Drag and drop screenshot image to Dolphin (or other app):

1. Take screenshot
2. Open Dolphin, create a new directory and show it
3. Use mouse and drag the screenshot image into the directory in Dolphin
4. Check file name used for the created file

Expected:
Matching the filename pattern defined in the settings

Drag and drop multiple screenshots to Dolphin (or other app):

1. Edit filename pattern settings to something without variables (so the same name would be used for every screenshot during testing)
2. Open Dolphin, create a new directory and show it
3. Take screenshot
4. Use mouse and drag the screenshot image into the directory in Dolphin
5. Take another screenshot
6. Use mouse and drag the screenshot image into the directory in Dolphin

Expected:
No filename conflicts.

Thanks for testing, @alexeymin. Feels better to push with at least knowing one person having had a go at the patch, with positive results :)