diff --git a/windows/CMakeLists.txt b/windows/CMakeLists.txt
index f4a10998..739c1300 100644
--- a/windows/CMakeLists.txt
+++ b/windows/CMakeLists.txt
@@ -38,6 +38,7 @@ list(APPEND _LIBUI_SOURCES
 	windows/main.cpp
 	windows/menu.cpp
 	windows/multilineentry.cpp
+	windows/opentype.cpp
 	windows/parent.cpp
 	windows/progressbar.cpp
 	windows/radiobuttons.cpp
diff --git a/windows/opentype.cpp b/windows/opentype.cpp
index 4273b80f..21e681b7 100644
--- a/windows/opentype.cpp
+++ b/windows/opentype.cpp
@@ -1,8 +1,10 @@
 // 11 may 2017
 #include "uipriv_windows.hpp"
 
+typedef std::map<uint32_t, uint32_t> tagmap;
+
 struct uiOpenTypeFeatures {
-	xxxx;
+	tagmap *tags;
 };
 
 uiOpenTypeFeatures *uiNewOpenTypeFeatures(void)
@@ -10,13 +12,13 @@ uiOpenTypeFeatures *uiNewOpenTypeFeatures(void)
 	uiOpenTypeFeatures *otf;
 
 	otf = uiNew(uiOpenTypeFeatures);
-	xxxx;
+	otf->tags = new tagmap;
 	return otf;
 }
 
 void uiFreeOpenTypeFeatures(uiOpenTypeFeatures *otf)
 {
-	xxxxxx;
+	delete otf->tags;
 	uiFree(otf);
 }
 
@@ -25,28 +27,79 @@ uiOpenTypeFeatures *uiOpenTypeFeaturesClone(uiOpenTypeFeatures *otf)
 	uiOpenTypeFeatures *out;
 
 	out = uiNew(uiOpenTypeFeatures);
-	xxxxxx;
+	out->tags = new tagmap;
+	*(out->tags) = *(otf->tags);
 	return out;
 }
 
+#define mktag(a, b, c, d) ((uint32_t) DWRITE_MAKE_OPENTYPE_TAG(a, b, c, d))
+
 void uiOpenTypeFeaturesAdd(uiOpenTypeFeatures *otf, char a, char b, char c, char d, uint32_t value)
 {
+	(*(otf->tags))[mktag(a, b, c, d)] = value;
 }
 
+// TODO what should happen if a/b/c/d isn't defined?
+// TODO what does std::map do if a/b/c/d isn't defined?
 void uiOpenTypeFeaturesRemove(uiOpenTypeFeatures *otf, char a, char b, char c, char d)
 {
+	otf->tags->erase(mktag(a, b, c, d));
 }
 
 int uiOpenTypeFeaturesGet(uiOpenTypeFeatures *otf, char a, char b, char c, char d, uint32_t *value)
 {
+	tagmap::const_iterator iter;
+
+	iter = otf->tags->find(mktag(a, b, c, d));
+	if (iter == otf->tags->end())
+		return 0;
+	*value = iter->second;
+	return 1;
 }
 
 void uiOpenTypeFeaturesForEach(uiOpenTypeFeatures *otf, uiOpenTypeFeaturesForEachFunc f, void *data)
 {
+	tagmap::const_iterator iter, end;
+
+	end = otf->tags->end();
+	for (iter = otf->tags->begin(); iter != end; iter++) {
+		uint8_t a, b, c, d;
+
+		a = (uint8_t) (iter->first & 0xFF);
+		b = (uint8_t) ((iter->first >> 8) & 0xFF);
+		c = (uint8_t) ((iter->first >> 16) & 0xFF);
+		d = (uint8_t) ((iter->first >> 24) & 0xFF);
+		// TODO handle return value
+		(*f)((char) a, (char) b, (char) c, (char) d,
+			iter->second, data);
+	}
 }
 
+// TODO wait, is this function even necessary? how do we unify attributes??
 int uiOpenTypeFeaturesEqual(uiOpenTypeFeatures *a, uiOpenTypeFeatures *b)
 {
+	// TODO make sure this is correct
+	return *(a->tags) == *(b->tags);
 }
 
-// TODO put the internal function to produce a backend object from one here
+IDWriteTypography *otfToDirectWrite(uiOpenTypeFeatures *otf)
+{
+	IDWriteTypography *dt;
+	tagmap::const_iterator iter, end;
+	DWRITE_FONT_FEATURE dff;
+	HRESULT hr;
+
+	hr = dwfactory->CreateTypography(&dt);
+	if (hr != S_OK)
+		logHRESULT(L"error creating IDWriteTypography", hr);
+	end = otf->tags->end();
+	for (iter = otf->tags->begin(); iter != end; iter++) {
+		ZeroMemory(&dff, sizeof (DWRITE_FONT_FEATURE));
+		dff.nameTag = (DWRITE_FONT_FEATURE_TAG) (iter->first);
+		dff.parameter = (UINT32) (iter->second);
+		hr = dt->AddFontFeature(dff);
+		if (hr != S_OK)
+			logHRESULT(L"error adding OpenType feature to IDWriteTypography", hr);
+	}
+	return dt;
+}
diff --git a/windows/uipriv_windows.hpp b/windows/uipriv_windows.hpp
index f1de95cf..aa39dd07 100644
--- a/windows/uipriv_windows.hpp
+++ b/windows/uipriv_windows.hpp
@@ -162,3 +162,6 @@ extern ID2D1DCRenderTarget *makeHDCRenderTarget(HDC dc, RECT *r);
 
 // drawtext.cpp
 extern void fontdescFromIDWriteFont(IDWriteFont *font, uiDrawFontDescriptor *uidesc);
+
+// opentype.cpp
+extern IDWriteTypography *otfToDirectWrite(uiOpenTypeFeatures *otf);