BumpTop doesn't send the arguments to the widgets on startup

To test this, I tried putting the following line in some of my widgets:
ShowMessage ( ParamStr(1) );

They all show blank, instead of the argument, specified in widget.json.
When starting them trough an associated image, they all show the correct argument.

This is the start-up part from widget.json:
"startupApplication" : {
"path" : "sample.exe",
"args" : "startup"
}

As this could be some problem with my code, I tried to test it with a batch file, but this one didn't start at all with BumpTop startup. It worked when launched from an image.
This is the batch file:
echo %1%
pause

This is the start-up part from widget.json:
"startupApplication" : {
"path" : "sample.cmd",
"args" : "startup"
}

When I put an empty argument into "args", it started OK.

In all cases launching from associated image showed the correct argument.