See also workaround

When working with 10+ related PDFs, the linear tab bar makes it slow to locate the next document, breaking context and increasing cognitive load.​ Prior related ideas in this forum suggest better tab navigation but do not provide grouping within the current workflow.​

I propose collapsible tab grouping, similar to the feature in modern web browsers.

MVP: Allow users to create collapsible tab groups by assigning a short label to a tab. All tabs with the same label should be visually bundled, and the entire group should be collapsible into a single, labeled button on the tab bar. Group assignments and their state (collapsed/expanded) should be saved across sessions.

It could also leverage Sumatra’s existing multi-window workflow with commands, rather than adding drag-out logic with commands like Group: Move this label to new window, Group: Collect label from all windows

Acceptance criteria:

1. Right-click a tab -> "Add to group" -> Sub-menu lists existing groups and a "New group" option.
2. Selecting "New group" allows the user to type a label.
   • Tabs in the same group are visually bundled together on the tab bar.
   • This group bundle has a "group label" (like "AI" or "Social" in the images below). Clicking this label collapses all tabs in the group into that single button.
3. Clicking the collapsed group label expands the group, showing all its tabs on the tab bar again.
   • Group assignments and their collapsed/expanded state persist after restart via the standard settings mechanism.

Example from browser:

A group is shown expanded alongside other tabs:

The same bar, but with the groups collapsed into small labeled buttons:

Workaround

#5123 (comment): "The closest current ability is to use a PDF index of like minded PDFs and click to open from that grouped file OR use different folders and start summatra pdf as a folder specific app without keeping a common history , so one commandline -appdata startup per group folder".

A workaround is creating a "Workspace" folder for each of your projects and then create a Windows shortcut (.lnk) or a batch file (.bat) with Target:

C:\path\to\SumatraPDF.exe -appdata "C:\path\to\your\AI Research\.sumatra"

Now when opening the shortcut SumatraPDF will launch a session only for that project. It will save and restore only the tabs related to "AI Research," completely separate from your other projects.