Menu underline for signature selection

pdf-sign

@@ -159,7 +159,7 @@ def main(args):
                         signatureIndex(root.signatureControlVar.get())
                         update()
                 for index, filename in enumerate(signatures):
-                    placemenu.add_radiobutton(value=index, label=filename, variable=root.signatureControlVar, accelerator=(str(index+1) if index<9 else None), command=updateFromSignatureRadio)
+                    placemenu.add_radiobutton(value=index, label=f'{index+1}: {filename}', underline=0 if index<9 else None, variable=root.signatureControlVar, accelerator=(str(index+1) if index<9 else None), command=updateFromSignatureRadio)
                 placemenu.add_separator()
             placemenu.add_command(label='Enlarge signature', underline=0, accelerator='+', command=cmd_enlargeSignature)
             placemenu.add_command(label='Shrink signature', underline=0, accelerator='-', command=cmd_shrinkSignature)