Bug 169748 - Tabs shifted forward when negative first-line value used
Summary: Tabs shifted forward when negative first-line value used
Status: RESOLVED WONTFIX
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Impress (show other bugs)
Version:
(earliest affected)
26.2.0.0 alpha0+ master
Hardware: All All
: medium normal
Assignee: Not Assigned
URL:
Whiteboard:
Keywords:
Depends on:
Blocks: Tab-Stops
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Reported: 2025-11-29 20:16 UTC by Eyal Rozenberg
Modified: 2025-12-10 10:32 UTC (History)
3 users (show)

See Also:
Crash report or crash signature:


Attachments
Presentation with a textbox, text and tab (69.16 KB, application/vnd.oasis.opendocument.presentation-flat-xml)
2025-12-10 07:18 UTC, Eyal Rozenberg
Details

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Description Eyal Rozenberg 2025-11-29 20:16:13 UTC
If I have a tab set for a paragraph in my text box, and I then use the Format > Paragraph dialog to set a negative First Line indent and a positive general indent - the tab will be moved forward by the absolute value of the first-line indent. That should not happen. 

This happens even if I then select multiple paragraphs, after having indented, and re-set the first line and general indentation.

(and there seems to be general flakiness with tabs and indented paragraphs in Impress.)
Comment 1 jcline 2025-12-10 04:17:46 UTC
repro in Version: 25.8.3.2 (X86_64)
Build ID: 8ca8d55c161d602844f5428fa4b58097424e324e
CPU threads: 32; OS: Windows 11 X86_64 (build 26100); UI render: Skia/Vulkan; VCL: win
Locale: en-US (en_US); UI: en-US
Calc: CL threaded

no repro Version: 26.8.0.0.alpha0+ (X86_64) / LibreOffice Community
Build ID: 680(Build:0)
CPU threads: 32; OS: Windows 11 X86_64 (build 26100); UI render: Skia/Vulkan; VCL: win
Locale: en-US (en_US); UI: en-US
Calc: CL threaded
Comment 2 Buovjaga 2025-12-10 06:13:46 UTC
Eyal: can you re-test with a fresh build?
Comment 3 Eyal Rozenberg 2025-12-10 07:18:36 UTC
Created attachment 204554 [details]
Presentation with a textbox, text and tab

So, first, I can still reproduce with:

Version: 26.2.0.0.alpha1+ (X86_64) / LibreOffice Community
Build ID: 0686b1972806fe8b711de5ba64039fb38cd14889
CPU threads: 4; OS: Linux 6.12; UI render: default; VCL: gtk3
Locale: en-IL (en_IL); UI: en-US

I'm attaching a presentation with a textbox, some text, and a tab at 3cm. When I set an indent of 1cm and first-line of -1cm, the tab moves from 3cm to 4cm.
Comment 4 Eyal Rozenberg 2025-12-10 07:19:55 UTC
But, on second thought - I'm not sure the moving of the tabs is wrong. Maybe it's the first-line tab which should be ignored and the tabs be interpreted relative to the indented start of the paragraph.
Comment 5 Heiko Tietze 2025-12-10 09:06:52 UTC
(In reply to Eyal Rozenberg from comment #3)
> When I set an indent of 1cm and first-line of -1cm, the tab moves from 3cm
> to 4cm.

A configured tab distance changes after the paragraph indentation is modified. The value of 3 becomes 4 if Before Text is set to 1, and to -0.95 if the tab value is 0.05 and the 1 before becomes 0. Don't see a reason for this as we could just add the tab value to the paragraph indentation, rather than mixing the two.
Comment 6 Mike Kaganski 2025-12-10 10:19:52 UTC
The behavior that tabs are relative to the paragraph's left boundary (which is its left indent, not its first line indent) is part of API, and changing that would create infinite number of problems - in UI, in existing documents' formatting, in macros. There is TabsRelativeToIndent compat option, changing the behavior (but it's different). Adding another compat option would still not fix the problem reported here, because making that new behavior the default would still have the negative impact described above - would be incompatible change from PoV of API.
Comment 7 Eyal Rozenberg 2025-12-10 10:32:32 UTC
(In reply to Mike Kaganski from comment #6)
> The behavior that tabs are relative to the paragraph's left boundary (which
> is its left indent, not its first line indent) is part of API,

Accepting that, there is still the question of what the tab dialog is supposed to show. Right now, it shows a value that's not relative to the indent, but ignoring the indent; and that value gets changed, when we change the indent. Is that appropriate?

I am willing to accept the status of quo of "Yes", but I'm not sure.

We should also think about what happens when we set a tab position for multiple paragraphs at once. That might justify why it's better to show the absolute rather than indent-relative tab positions.