Comment 6 for bug 1010263

It happens with multiple .xls files, and still happens if I save to .gnumeric, quit, open file.gnumeric, change one cell, click Save, then click the x to close the window. So it doesn't seem related to format.

In fact, you don't even need a file. Run gnumeric with no arguments. Enter a in cell a1, then click Save. The Save as dialog comes up; choose a filename, leave the format as .gnumeric and let it save to filename.gnumeric. Then click the windowmanager x. The confirmation dialog comes up.