Backends: Win32: Fix _WIN32_WINNT < 0x0600 (MinGW defaults to 0x502 == Windows 2003). (#3183)

docs/CHANGELOG.txt

@@ -51,6 +51,7 @@ Other Changes:
   Set to FLT_MAX to only display a close button when selected (merely hovering is not enough).
   Set to an intermediary value to toggle behavior based on width (same as Firefox).
 - Backends: Win32: Support for #define NOGDI, won't try to call GetDeviceCaps(). (#3137, #2327)
+- Backends: Win32: Fix _WIN32_WINNT < 0x0600 (MinGW defaults to 0x502 == Windows 2003). (#3183)
 - Backends: OpenGL: Fixed handling of GL 4.5+ glClipControl(GL_UPPER_LEFT) by inverting the
   projection matrix top and bottom values. (#3143, #3146) [@u3shit]
 - Backends: Vulkan: Fixed error in if initial frame has no vertices. (#3177)

examples/imgui_impl_win32.cpp

@@ -359,7 +359,7 @@ IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hwnd, UINT msg, WPARA
 #if !defined(_versionhelpers_H_INCLUDED_) && !defined(_INC_VERSIONHELPERS)
 static BOOL IsWindowsVersionOrGreater(WORD major, WORD minor, WORD sp)
 {
-    OSVERSIONINFOEXW osvi = { sizeof(osvi), major, minor, 0, 0, { 0 }, sp };
+    OSVERSIONINFOEXW osvi = { sizeof(osvi), major, minor, 0, 0, { 0 }, sp, 0, 0, 0, 0 };
     DWORD mask = VER_MAJORVERSION | VER_MINORVERSION | VER_SERVICEPACKMAJOR;
     ULONGLONG cond = ::VerSetConditionMask(0, VER_MAJORVERSION, VER_GREATER_EQUAL);
     cond = ::VerSetConditionMask(cond, VER_MINORVERSION, VER_GREATER_EQUAL);
@@ -405,7 +405,9 @@ void ImGui_ImplWin32_EnableDpiAwareness()
             return;
         }
     }
-    SetProcessDPIAware();
+#if _WIN32_WINNT >= 0x0600
+    ::SetProcessDPIAware();
+#endif
 }
 
 #if defined(_MSC_VER) && !defined(NOGDI)