Enhance the worflow related to how we show/hide/enable/disable keyframes on effect properties
Steps to reproduce:
- Pitivi Flatpak version 0.999.0 downloaded a few days ago, GES 126.96.36.199, GTK+ 3.22, GStreamer 188.8.131.52
- Make a short screencast under GNOME by pressing Ctrl+Alt+Shift+R and pressing that again after a few seconds
- Under "Media Library" in Pitivi, click "Import", choose that screencast file, and click "Add" in the file chooser
- Drag that screencast file to "Layer 0"
- Click on that file in "Layer 0"
- Click "Effect Library"
- Scroll down to "Lens Correction" effect
- Drag "Lens Correction" effect to the "Effects" section in the "Clip" pane
- See that several values are available such as "brightness", "correctonnearcenter", etc
- Click the "Show keyframes for this value" button
- See that the button turns from ◇ to ◆
- Click the button again
Expected outcome: Button turns from ◆ to ◇
Actual outcome: Button stays ◆
This is especially confusing when you also enabled showing another value's keyframes and cannot see anymore which effect's value's keyframe you are editing in the layer.