Commit 100504d2f5 introduced using GetDpiForWindow(). Unfortunately NOTEPAD_LoadSettingFromRegistry is executed when the main window is not yet created, resulting in having Globals.lfFont.lfHeight=0. This is later stored in the registry in iPointSize=0.
In a fresh wine prefix there are not yet registry values created, therefore the first run of notepad does not show this problem, and iPointSize is saved with a sane value to the registry.
Having Globals.lfFont.lfHeight=0 manifests for example in cups PDF prints being a single empty page.
The check of point_size for having a non-zero value should also fix wine prefixes which have already a stored registry value of iPointSize=0.
Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=55852
CC: @petrathekat