diff --git a/doc/controls.md b/doc/controls.md
index 1b899663..f286acda 100644
--- a/doc/controls.md
+++ b/doc/controls.md
@@ -114,10 +114,12 @@ This function can only be used to set the parent of an unparented control or to
 It is a programmer error to pass `NULL` or a non-control for `c`.
 
 TODO circular parenting
+TODO self-parenting
+TODO top-levels and parenting
 
 **For control implementations**: You would call this when adding a control to your container, preferably before actually doing the OS-level work involved. Likewise, call this when removing a child, preferably after doing the OS-level work involved.
 
-TODO do things this way to avoid needing to check if reparenting from a container implementation, or do that manually each time?
+TODO do things this way to avoid needing to check if reparenting from a container implementation, or do that manually each time? we used to have uiControlVerifySetParent()...
 
 ## `uiControlImplData()`
 
diff --git a/test/controls_errors.cpp b/test/controls_errors.cpp
index 686cfded..a7764879 100644
--- a/test/controls_errors.cpp
+++ b/test/controls_errors.cpp
@@ -147,9 +147,59 @@ static const struct checkErrorCase casesAfterOSVtable[] = {
 	{
 		"uiControlFree() with a uiControl that still has a parent",
 		[](void) {
-			// TODO
+			uiControl *c, *d;
+
+			c = uiNewControl(testControlType, NULL);
+			d = uiNewControl(testControlType, NULL);
+
+			// this should fail
+			uiControlSetParent(c, d);
+			uiControlFree(c);
+
+			uiControlSetParent(c, NULL);
+			uiControlFree(d);
+			uiControlFree(c);
 		},
-		"TODO",
+		"uiControlFree(): cannot be called on a control with has a parent",
+	},
+
+	{
+		"uiControlSetParent() with a NULL uiControl",
+		[](void) {
+			uiControlSetParent(NULL, NULL);
+		},
+		"uiControlSetParent(): invalid null pointer for uiControl",
+	},
+	{
+		"uiControlSetParent() to unparent an already parentless control",
+		[](void) {
+			uiControl *c;
+
+			c = uiNewControl(testControlType, NULL);
+			uiControlSetParent(c, NULL);
+			uiControlFree(c);
+		},
+		"uiControlSetParent(): cannot set a control with no parent to have no parent",
+	},
+	{
+		"uiControlSetParent() to reparent an already parented control",
+		[](void) {
+			uiControl *c, *d, *e;
+
+			c = uiNewControl(testControlType, NULL);
+			d = uiNewControl(testControlType, NULL);
+			e = uiNewControl(testControlType, NULL);
+
+			// this should fail
+			uiControlSetParent(c, d);
+			uiControlSetParent(c, e);
+
+			uiControlSetParent(c, NULL);
+			uiControlFree(e);
+			uiControlFree(d);
+			uiControlFree(c);
+		},
+		"uiControlSetParent(): cannot set a control with a parent to have another parent",
 	},
 
 	{