do not export inline function, it causes problems on some compiers

imgui.h

@@ -1022,7 +1022,7 @@ struct ImGuiTextEditCallbackData
     // NB: Helper functions for text manipulation. Calling those function loses selection.
     IMGUI_API void    DeleteChars(int pos, int bytes_count);
     IMGUI_API void    InsertChars(int pos, const char* text, const char* text_end = NULL);
-    IMGUI_API bool    HasSelection() const { return SelectionStart != SelectionEnd; }
+    bool    HasSelection() const { return SelectionStart != SelectionEnd; }
 };
 
 // Resizing callback data to apply custom constraint. As enabled by SetNextWindowSizeConstraints(). Callback is called during the next Begin().