https://bugs.kde.org/show_bug.cgi?id=520812
Bug ID: 520812
Summary: Butchered Save after Dragging Large Number of Clips
Classification: Applications
Product: kdenlive
Version First 26.04.1
Reported In:
Platform: Ubuntu
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: Timeline & Editing
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 192724
--> https://bugs.kde.org/attachment.cgi?id=192724&action=edit
Project timeline immediately after save, comparing before and after app
relaunch
DESCRIPTION
I found this bug while working on a video project for my YouTube channel. When
editing large projects with hundreds of clips, dragging too many at once can
trigger undefined app state with extremely subversive cascade effects.
I've prepared a MWE with a video screen capture of me reproducing the bug (or
bugs?). All related files are available here:
https://drive.google.com/drive/folders/1I9-iCmwrv5QnTU8IiqFqhVcxyQ9hURe9?usp=sharing
STEPS TO REPRODUCE
This is how I was able to reproduce the bug. Perhaps these steps could be
reduced further.
1. Open or create a project with a large cluster of clips. (For me, > 400 clips
can reliably reproduce; see 'mwe.kdenlive' at the Google Drive link above.)
2. Move a single nearby clip to create a gap in the timeline adjacent to the
large cluster
3. Select the cluster of clips
4. Zoom in on the gap
5. Click and drag the cluster of clips to fill the gap, which should freeze the
app long enough that GNOME opens the "Force quit?" dialog (note: keep the mouse
button held until the dialog appears)
6. Let go of the mouse button
7. Wait for the app to unfreeze
*************************************************
NOTE: This is the point when the undefined state begins,
identified by the app UI failing to recognize that you let
go of the mouse button. The cursor will still look like a
fist, as though you're still dragging the clips.
*************************************************
8. While the cursor shows a fist but your mouse button is unpressed, press
Ctrl+Z on your keyboard. This will NOT undo Step 5 above as expected.
9. Click and drag the cluster a small amount, and wait for the app to
update/unfreeze again.
10. Click a new clip in the cluster to change the primary one in the selection.
11. Press Ctrl+Z on your keyboard. This will appear to undo Step 9 above.
12. Press Ctrl+Z again. Like in Step 8 above, this will NOT undo Step 5;
internally, it seems instead to undo the clip move you did in Step 2. (Might be
redundant with Step 8?)
13. Zoom out and observe that the single clip you moved in Step 2 is now
completely GONE.
14. If the app thinks you have no changes, then move something and move it back
to simulate unsaved changes. (Only necessary in MWE with limited Undo history.)
15. Save the project.
OBSERVED RESULT
Your save is now invisibly butchered. Your beautiful project timeline is a lie,
and if you close/relaunch the app you will see a hideously butchered mess:
clips crashed into each other and pushed out of sync, grouped clips are now
ungrouped, etc.
EXPECTED RESULT
The visible state of the project when you save should actually be what is
saved, and should be unchanged when you relaunch the app.
GOOGLE DRIVE FILES
├── 1-IMG_9998-30fps.mp4 (used in MWE)
├── bg-cycles-HD.mp4 (used in MWE)
├── mwe-after.kdenlive (project afterward)
├── mwe.kdenlive (project beforehand)
├── save_corruption-after.png (timeline screenshot)
├── save_corruption-anim.gif (timeline before/after comparison)
├── save_corruption-before.png (timeline screenshot)
└── Screencast From 2026-05-29 23-02-43.mp4 (screen capture)
SOFTWARE/OS VERSIONS
Kdenlive: 26.04.1
Kdenlive
MLT: 7.39.0
FFmpeg
KDE Frameworks: 6.24.0
Qt: Using 6.10.2 and built against 6.10.2
Flatpak
KDE Flatpak runtime (Wayland)
Build ABI: x86_64-little_endian-lp64
Kernel: linux 6.17.0-35-generic
ADDITIONAL INFORMATION
- **Hardware Model:** Acer Predator PH317-55
- **Memory:** 32.0 GiB
- **Processor:** 11th Gen Intel® Core™
i7-11800H × 16
- **Graphics:** Intel® UHD Graphics (TGL
GT1)
- **Graphics 1:** zink Vulkan 1.4(NVIDIA
GeForce RTX™ 3070 Laptop GPU (NVK GA104))
- **Disk Capacity:** 1.0 TB
- **Firmware Version:** V1.12
- **OS Name:** Ubuntu 25.10
- **OS Build:** (null)
- **OS Type:** 64-bit
- **GNOME Version:** 49
- **Windowing System:** Wayland
- **Kernel Version:** Linux 6.17.0-35-generic
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