fix: refresh mpl interactive plots when browser tab becomes visible#8287
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dmadisetti merged 1 commit intomainfrom Feb 12, 2026
Merged
fix: refresh mpl interactive plots when browser tab becomes visible#8287dmadisetti merged 1 commit intomainfrom
dmadisetti merged 1 commit intomainfrom
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Closes #2092 ## Problem When `mo.mpl.interactive()` plots are rendered while the browser tab is in the background (minimized or switched to another tab), the plots appear blank. This is because browsers throttle or skip canvas rendering in background tabs, so the image data sent by matplotlib's WebAgg server over WebSocket is effectively lost. ## Fix Added a `visibilitychange` event listener in the matplotlib iframe's HTML template. When the browser tab becomes visible again, it sends a `refresh` message to the matplotlib WebAgg server. This triggers a full figure redraw (`_force_full = True` + `draw_idle()`) that sends fresh canvas data back to the browser, ensuring the plot is always up-to-date when the user returns.
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Pull request overview
This PR fixes a bug where mo.mpl.interactive() plots appear blank when rendered while the browser tab is in the background. The fix adds a visibilitychange event listener that refreshes the plot when the tab becomes visible again.
Changes:
- Added JavaScript event listener in the matplotlib iframe template to detect when the browser tab becomes visible
- Added test coverage to verify the visibilitychange listener is present in the generated HTML
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| marimo/_plugins/stateless/mpl/_mpl.py | Added visibilitychange event listener to refresh matplotlib figures when browser tab becomes visible |
| tests/_plugins/stateless/test_mpl.py | Added regression test to verify the visibilitychange listener is present in the template |
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Feb 12, 2026
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Closes #2092
Closes #4435
Problem
When
mo.mpl.interactive()plots are rendered while the browser tab is in thebackground (minimized or switched to another tab), the plots appear blank.
This is because browsers throttle or skip canvas rendering in background tabs,
so the image data sent by matplotlib's WebAgg server over WebSocket is
effectively lost.
Fix
Added a
visibilitychangeevent listener in the matplotlib iframe's HTMLtemplate. When the browser tab becomes visible again, it sends a
refreshmessage to the matplotlib WebAgg server. This triggers a full figure redraw
(
_force_full = True+draw_idle()) that sends fresh canvas data back tothe browser, ensuring the plot is always up-to-date when the user returns.