When you use the built-in HelpProvider or try to show a help popup using Help.ShowPopup, if you specify a string containing special Unicode characters like Persian or Arabic characters, the popup doesn't show those characters correctly.
The because of two problems:
- The default font which is used by underlying API of the HelpProvider doesn't support unicode characters
- The underlying API of the HelpProvider doesn't support Unicode.
The first problem is in Help class(.NET 4.X, .NET 5) which has created the HH_POPUP but hasn't specified any font for it. As a result a default font which doesn't support Unicode characters will be used.
- A possible fix is using a default font like
SystemFonts.CaptionFontwhich supports Unicode characters.
For the second problem, you need to change a setting in Windows, to do so:
- Go to Control Panel → Region → Administratve tab, then in the section "Language for non-Unicode programs", click on "Change system locale ..." button and then in the next dialog, choose the language of your choice, for example Persian.
In this example I've created a HelpProvider2 component which supports unicode characters:
It also exposes Font, ForeColor and BackColor properties:
The example also contains a HelpExtensions.ShowPopup2 which can be used instead of Help.ShowPopoup:
HelpExtensions.ShowPopup2(button1, "متن آزمایشی", Control.MousePosition);