In a fairly standard setup, the toolbar doesn’t leave much room for the file name in between the master icons and tool icons…with the part of the name which is usually the most important (date/version/description) being truncated. The full name only visible on hover or when the window gets narrow enough to display the full file name on its own line above the icons and tools.
from AppKit import NSWindowToolbarStyleExpanded
Font.parent.windowController().window().setToolbarStyle_(NSWindowToolbarStyleExpanded)
It will switch back now and then, so you need to find a way to reset it.
When you make the window a bit smaller, it will switch to the expanded style. But there is a window size where there might not be enough space for the title but it is not switching, yet.
