Integrated the Common Controls 6 manifest into libui.dll. While it does work, themes don't work, and I wonder if it's because of isolation awareness. Time to write an nmakefile!

windows/libui.manifest

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
+<assemblyIdentity
+    version="1.0.0.0"
+    processorArchitecture="*"
+    name="CompanyName.ProductName.YourApplication"
+    type="win32"
+/>
+<description>Your application description here.</description>
+<dependency>
+    <dependentAssembly>
+        <assemblyIdentity
+            type="win32"
+            name="Microsoft.Windows.Common-Controls"
+            version="6.0.0.0"
+            processorArchitecture="*"
+            publicKeyToken="6595b64144ccf1df"
+            language="*"
+        />
+    </dependentAssembly>
+</dependency>
+</assembly>
+

windows/resources.rc

@@ -5,6 +5,9 @@
 // this is a UTF-8 file
 #pragma code_page(65001)
 
+// this is the Common Controls 6 manifest
+ISOLATIONAWARE_MANIFEST_RESOURCE_ID RT_MANIFEST "libui.manifest"
+
 // this is the dialog template used by tab pages; see windows/tabpage.c for details
 rcTabPageDialog DIALOGEX 0, 0, 100, 100
 STYLE DS_CONTROL | WS_CHILD | WS_VISIBLE

windows/winapi.h

@@ -8,6 +8,8 @@
 // see https://github.com/golang/go/issues/9916#issuecomment-74812211
 #define INITGUID
 #define _USE_MATH_DEFINES
+// for the manifest
+#define ISOLATION_AWARE_ENABLED 1
 // get Windows version right; right now Windows Vista
 #define WINVER 0x0600				/* according to Microsoft's winnls.h */
 #define _WIN32_WINNT 0x0600		/* according to Microsoft's sdkddkver.h */