Hi @ingurgite,
the `Journal.open()` invocation tries to open the Journal in the active container, the default window in this case. The default window should open the Journal window as a modal window but it fails if executed in the WillShow event because a window that is not already added to the window's hierarchy cannot open a modal window.

A safer way to change the default window could be to use the loadContainer() method of the Application object, for example with the following code:

var screen = "journal"

if (screen == "journal")
{
	console.log("HERE: opening journal")
	App.loadContainer(Journal)
}

This command replaces the root window (default window) with the Journal window.