Simple to reproduce. In my case I has a wide string like this: L"abcd&efgh"
When I hover over the variable name in the sourcecode in the debugger, the ampersand is not shown in the tooltip text. In the Auto window tab, the same variable is displayed correctly with the ampersand.
A tooltip feature, not a bug.
QuoteMany applications create toolbars containing tools that correspond to menu commands. For such tools, it is convenient for the tooltip control to display the same text as the corresponding menu item. The system automatically strips the ampersand (&) accelerator characters from all strings passed to a tooltip control, and terminates the string at the first tab character (\t), unless the control has the TTS_NOPREFIX style.
OK, I will add TTS_NOPREFIX (for some future version). Less surprising, I guess...