It seems that THTMLHint component doesnt handle character '|' correctly. The string is terminated just before this character. So when I set Hint property of form to "(135 | 138)", the hint shows only "(135 ".
This is a generic hint issue in the Delphi VCL framework hint handling itself.
When you set such hint using the pipe character on a control without using THTMLHint, it will also cut off at the pipe character. This is unfortunately not something we can solve at THTMLHint level as the VCL doesn't pass the entire hint string to THTMLHint.
Whats weird Delphi handles the dental click Unicode character (code 0x1C0) which looks very similarly in the same way. So probably I will use letter I or broken bar ¦ as replacement character.