Minus key does useless action when layers palette focused

When I have the layers palette focused and hit "-" (minus) to zoom out, the layers palette instead brings up a useless little text input field with the "-" in it. I don't have any layer names selected, so it's not me (for example) accidentally renaming a layer. I can't even tell what this field is -- it doesn't seem to search, because when I hit return for a bit of text that I know is present in the layer names, the field just goes away. No error message pops up.

Ideally, Inkscape should continue to zoom out when I hit the "-" key. Instead, it brings up this useless little field and I have to move the mouse focus to the main drawing field. This interrupts my workflow quite badly, forcing me to shift tools and then shift focus many times an hour.

I'm using Inkscape 0.48.3.1 r9886 on Linux Mint 14. This error occurs with all documents.

Steps to reproduce the error:
1. Open a document.
2. Focus on the main drawing area. Hit "-" key. Inkscape should zoom out.
3. Focus or click on layer palette.
4. Hit "-" key. Inkscape brings up strange text input field with "-" in it.