This may be related to the sandboxing of Installer Plugins. It might be preferable to only disable the Continue button if the conditions are not met and invite the user to quit the application. Side note: The issue when you check requirements through an Installer Plugin is that these requirements will not be checked when the installation is run from the command line or through a deployment solution (b/c the Plugin will not be loaded). So this would end up in the erroneous installations you mentioned.

FB8913004 Side note: In macOS BS, the default icon is apparently built from a SF Symbol. But using a NSImage built from a SF Symbol does not display the image but keeps displaying the magnifying glass. Sigh.

I think it's a bug in AppKit that exists in 10.14.x, 10.15.x and 11.0.1. The NSTextView scrolling methods do not seem to take into account vertical rulers and horizontal scrolling at the same time by assuming the scroll point will always have x = 0 for key scrolling that goes through the scrollDown: and scrollUp: methods. 2. The following code looks like to address the issue and work for 10.14 and later (on Intel at least). It can certainly be improved. (void)_scrollDown:(CGFloat)inOffset {     NSScrollView * tScrollView=self.enclosingScrollView;     NSView * tDocumentView=tScrollView.documentView;     NSRulerView * tVerticalRulerView=tScrollView.verticalRulerView;     if (self!=tDocumentView ||         tVerticalRulerView==nil ||         tScrollView.horizontalScroller.isHidden==YES)     {         [super _scrollDown:inOffset];         return;     }     NSRect tOldFrame=tDocumentView.frame;          /* Offset the text view frame to take into account the vertical ruler width */              NSRect tNewFrame=tOldFrame;              tNewFrame.origin.x-=NSWidth(tVerticalRulerView.frame);              self.frame=tNewFrame;          [super _scrollDown:inOffset];     /* Restore the text view frame */     self.frame=tOldFrame; }

https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/SearchFields/Articles/MenuTemplate.html#//apple_ref/doc/uid/20002245-BABFIBIA

Some additional info: using the vertical scroller with the mouse to scroll vertically just works fine (dragging the thumb or clicking below the thumb). using the Home and End keys just works fine.