Comment 1 for bug 1741133

This definitely happens to me too, for as far back as I can remember. It still happens in version 0.92.3.

I'm running Lubuntu 16.04. I can perform the following steps to reproduce the problem:

1. Close all dialogs.
2. Close Inkscape.
3. Open it again.
4. Open the Fill and Stroke dialog by double-clicking the color data section in the status bar.
5. Open the Layers dialog by going to the Layer/Layers... menu.
6. Open the Real Time Path Effects dialog by going to the Path/Real Time Path Effects... menu.
7. If they are not already, drag all dialogs so that they are floating.
8. Drag the Layers dialog such that it snaps to the top-right side of the Inkscape window.
9. Drag the Stroke and Fill dialog such that it snaps to below the Layers dialog (the preview should place the rectangle on the lower portion of the Layers dialog).
10. Drag the Real Time Path Effects dialog such that it snaps with the Stroke and Fill dialog (the preview should place the rectangle on the center of the Stroke and Fill dialog).
11. Close Inkscape.
12. Open it again.

The Real Time Path Effects dialog should now be grouped in with the Layers dialog. If I close it and open it once more, all three of them get bundled in the same group.

I've tried right-clicking the Layers dialog and choosing Lock, but the problem still occurs.