diff --git a/windows/GNUfiles.mk b/windows/GNUfiles.mk
index 48fe7da3..b0387a52 100644
--- a/windows/GNUfiles.mk
+++ b/windows/GNUfiles.mk
@@ -20,7 +20,6 @@ CFILES += \
 	windows/draw.c \
 	windows/entry.c \
 	windows/events.c \
-	windows/fontbutton.c \
 	windows/group.c \
 	windows/init.c \
 	windows/label.c \
@@ -45,6 +44,7 @@ CFILES += \
 CXXFILES += \
 	windows/drawtext.cpp \
 	windows/dwrite.cpp \
+	windows/fontbutton.cpp \
 	windows/fontdialog.cpp
 
 HFILES += \
diff --git a/windows/fontbutton.c b/windows/fontbutton.cpp
similarity index 85%
rename from windows/fontbutton.c
rename to windows/fontbutton.cpp
index 472cbcb6..25940e0f 100644
--- a/windows/fontbutton.c
+++ b/windows/fontbutton.cpp
@@ -1,8 +1,6 @@
 // 14 april 2016
 #include "uipriv_windows.h"
 
-// TODO implement a custom font dialog that uses DirectWrite?
-
 struct uiFontButton {
 	uiWindowsControl c;
 	HWND hwnd;
@@ -10,24 +8,28 @@ struct uiFontButton {
 	BOOL already;
 };
 
+static void onDestroy(uiFontButton *);
+
 uiWindowsDefineControlWithOnDestroy(
 	uiFontButton,							// type name
 	uiFontButtonType,						// type function
-	uiWindowsUnregisterWM_COMMANDHandler(this->hwnd);	// on destroy
+	onDestroy(this);						// on destroy
 )
 
+static void onDestroy(uiFontButton *b)
+{
+	uiWindowsUnregisterWM_COMMANDHandler(b->hwnd);
+	destroyFontDialogParams(&(b->params));
+}
+
 static void updateFontButtonLabel(uiFontButton *b)
 {
-	// TODO make this dynamically sized
-	// TODO also include the style, but from where? libui or DirectWrite?
-	WCHAR text[1024];
-	WCHAR *family;
+	WCHAR *text;
 
-	family = toUTF16(b->params.desc.Family);
-	_snwprintf(text, 1024, L"%s %s %g", family, b->params.outStyleName, b->params.desc.Size);
-	uiFree(family);
+	text = fontDialogParamsToString(&(b->params));
 	// TODO error check
 	SendMessageW(b->hwnd, WM_SETTEXT, 0, (LPARAM) text);
+	uiFree(text);
 
 	// changing the text might necessitate a change in the button's size
 	uiWindowsControlQueueRelayout(uiWindowsControl(b));
@@ -83,6 +85,9 @@ static void defaultOnClicked(uiButton *b, void *data)
 }
 #endif
 
+// TODO document that GetFont returns a NEW instance each time
+// TODO document that the Handle of a Font may not be unique
+
 #if 0
 TODO
 void uiButtonOnClicked(uiButton *b, void (*f)(uiButton *, void *), void *data)
diff --git a/windows/uipriv_windows.h b/windows/uipriv_windows.h
index af2854eb..49014873 100644
--- a/windows/uipriv_windows.h
+++ b/windows/uipriv_windows.h
@@ -170,12 +170,18 @@ extern void dwriteAttrToAttr(struct dwriteAttr *attr);
 extern void doDrawText(ID2D1RenderTarget *rt, ID2D1Brush *black, double x, double y, uiDrawTextLayout *layout);
 
 // fontdialog.cpp
+#ifdef __cplusplus
 struct fontDialogParams {
-	uiDrawTextFontDescriptor desc;
-	WCHAR *outStyleName;
+	IDWriteFont *font;
+	double size;
+	WCHAR *familyName;
+	WCHAR *styleName;
 };
 extern BOOL showFontDialog(HWND parent, struct fontDialogParams *params);
 extern void loadInitialFontDialogParams(struct fontDialogParams *params);
+extern void destroyFontDialogParams(struct fontDialogParams *params);
+extern WCHAR fontDialogParamsToString(struct fontDialogParams *params);
+#endif
 
 // d2dscratch.c
 extern ATOM registerD2DScratchClass(HICON, HCURSOR);