It gives some scrambled text as it is not send as UTF-16 text but UTF-8 text.
Create a new test project and add this view as an example:
Code:
Use Windows.pkg
Use DFClient.pkg
Deferred_View Activate_oTestToolTip for ;
Object oTestToolTip is a dbView
Set Border_Style to Border_Thick
Set Size to 200 300
Set Location to 2 2
Set Label to "TestToolTip"
Set psTitle of ghoToolTipController to "Test title"
Object oForm1 is a Form
Set Size to 13 100
Set Location to 13 101
Set psToolTip to "Test tool tip text"
End_Object
Cd_End_Object
The error shows like this:

To fix for now you can subclass the cToolTipController and fix the method your self:
Code:
// Replace the standard oToolTipController in your src file with an object of this class.
Class cToolTipControllerFix is a cToolTipController
// Eksample of a corrected method that takes a native utf-8 string and send as UTF-16 text message.
Procedure Set psTitle String sTitle
Integer iVoid iIcon
Pointer lpsTitle
Handle hToolTip
String sIcon
WString wsTitle
Set psTitle_private to sTitle
Move sTitle to wsTitle
// Icon & title must be set together. Determine what the icon is so we can set it.
// It will be either an icon ID for a standard icon, or an icon filename....
Get piIcon to iIcon
If (iIcon <> TTI_NONE) Begin
Set piIcon to iIcon // this will set the icon & title.
Procedure_Return
End
// Test if an icon filename is set....
Get psIcon_private to sIcon
If (sIcon <> "") Begin
Send LoadIcon sIcon // this will set icon & title.
Procedure_Return
End
// If we got here then there is no icon, just set the title then....
Get phToolTip to hToolTip
Move (SendMessage(hToolTip, TTM_SETTITLE, TTI_NONE, AddressOf(wsTitle))) to iVoid
End_Procedure
End_Class
Object oToolTipControllerFix is a cToolTipControllerFix
Move Self to ghoToolTipController
End_Object
The result:
