Fonts: fixed CalcWordWrapPositionA() fallback when width is too small to wrap with multibyte codepoints.. (#8540)

docs/CHANGELOG.txt

@@ -56,6 +56,8 @@ Other changes:
   CTRL+Tab windowing + pressing a keyboard key. (#8525)
 - Error Handling: added better error report and recovery for extraneous
   EndPopup() call. (#1651, #8499)
+- Fonts: fixed CalcWordWrapPositionA() fallback when width is too small to wrap:
+  would use a +1 offset instead of advancing to the next UTF-8 codepoint. (#8540)
 - Style, InputText: added ImGuiCol_InputTextCursor to configure color of
   the InputText cursor/caret. (#7031)
 - Misc: added extra operators to ImVec4 in IMGUI_DEFINE_MATH_OPERATORS block. (#8510) [@gan74]

imgui_draw.cpp

@@ -4027,7 +4027,7 @@ const char* ImFont::CalcWordWrapPositionA(float scale, const char* text, const c
     // Wrap_width is too small to fit anything. Force displaying 1 character to minimize the height discontinuity.
     // +1 may not be a character start point in UTF-8 but it's ok because caller loops use (text >= word_wrap_eol).
     if (s == text && text < text_end)
-        return s + 1;
+        return s + ImTextCountUtf8BytesFromChar(s, text_end);
     return s;
 }