Minor interface issue around dragging SVG images to a custom palette
You can drag images from the score to a custom palette by control shift dragging. This works.
If you're not holding the modifiers down when you click and subsequently do so while still mouse down, you can't drag the image onto the palette (rather the dragging seems to be limited to one axis). The behavior should not be different.
This is not important except that it may be the source of confusion around using custom palettes.