diff --git a/TODO.md b/TODO.md
index 73e2e15b..cfd298a4 100644
--- a/TODO.md
+++ b/TODO.md
@@ -10,9 +10,10 @@
 - make sure all terminology is consistent
 - 32-bit Mac OS X support (requires lots of code changes)
 - add a test for hidden controls when a window is shown
-- WS_CLIPCHILDREN
+- SWP_NOCOPYBITS (or was it WS_CLIPCHILDREN?)
 	- buttons not in tab get drawover issues
 	- buttons in tab without transparent drawing code get copied into the label when stack shown and rehidden
+- see if we can clean up the GTK+ backend
 
 ultimately:
 - make everything vtable-based
@@ -21,3 +22,4 @@ ultimately:
 		- figure out what to do about custom containers
 			- rename container to parent?
 		- make the code flow of all platforms fully symmetrical
+- add some sort of runtime type checking
diff --git a/unix/button.c b/unix/button.c
index ac6c9b43..d67b9a44 100644
--- a/unix/button.c
+++ b/unix/button.c
@@ -3,7 +3,7 @@
 
 struct button {
 	uiButton b;
-	void (*onClicked)(uiControl *, void *);
+	void (*onClicked)(uiButton *, void *);
 	void *onClickedData;
 };
 
@@ -38,7 +38,7 @@ static void setText(uiButton *b, const char *text)
 	gtk_button_set_label(BUTTON(b), text);
 }
 
-static void setOnClicked(uiButton *bb, void (*f)(uiControl *, void *), void *data)
+static void setOnClicked(uiButton *bb, void (*f)(uiButton *, void *), void *data)
 {
 	struct button *b = (struct button *) bb;
 
diff --git a/unix/checkbox.c b/unix/checkbox.c
index 5111c0ed..f3563a16 100644
--- a/unix/checkbox.c
+++ b/unix/checkbox.c
@@ -31,12 +31,12 @@ static void onDestroy(GtkWidget *widget, gpointer data)
 
 static char *getText(uiCheckbox *c)
 {
-	return g_strdup(gtk_button_get_label(CHECKBOX(c)));
+	return g_strdup(gtk_button_get_label(GTK_BUTTON(CHECKBOX(c))));
 }
 
 static void setText(uiCheckbox *c, const char *text)
 {
-	gtk_button_set_label(CHECKBOX(c), text);
+	gtk_button_set_label(GTK_BUTTON(CHECKBOX(c)), text);
 }
 
 static void setOnToggled(uiCheckbox *cc, void (*f)(uiCheckbox *, void *), void *data)
diff --git a/unix/newcontrol.c b/unix/newcontrol.c
index f7743f43..d23e1903 100644
--- a/unix/newcontrol.c
+++ b/unix/newcontrol.c
@@ -222,5 +222,4 @@ void uiUnixNewControl(uiControl *c, GType type, gboolean inScrolledWindow, gbool
 	gtk_widget_show_all(s->immediate);
 
 	c->Internal = s;
-	return c;
 }
diff --git a/unix/tab.c b/unix/tab.c
index 8332bbd2..bb168f56 100644
--- a/unix/tab.c
+++ b/unix/tab.c
@@ -43,7 +43,6 @@ static void addPage(uiTab *tt, const char *name, uiControl *child)
 
 uiTab *uiNewTab(void)
 {
-	uiControl *c;
 	struct tab *t;
 	GtkWidget *widget;
 
diff --git a/unix/window.c b/unix/window.c
index c030d87e..039feb7e 100644
--- a/unix/window.c
+++ b/unix/window.c
@@ -15,7 +15,7 @@ static gboolean onClosing(GtkWidget *win, GdkEvent *e, gpointer data)
 	struct window *w = (struct window *) data;
 
 	// return exact values just in case
-	if ((*(w->onClosing))(w, w->onClosingData))
+	if ((*(w->onClosing))(uiWindow(w), w->onClosingData))
 		return FALSE;
 	return TRUE;
 }