Pull Liquify out of the external window entirely... it would be much more useful integrated into the native UI. Add a liquify button to the Tools toolbar and ditch it from the Filter menu.
Having access to my typical brush-resizing shortcuts would be a lifesaver! It just makes more sense...
All of the buttons and tools in the Liquify panel could easily fit in the "Options" toolbar that runs across the top of the software. If any excess buttons wouldn't fit in the top Options toolbar, a Liquify panel could be created if necessary.
This is my #1 idea for the next version of Photoshop. There is no reason for Liquify to open a new window... none at all. Not anymore at least, if there ever was one.