Wrote up an untested implementation of a GtkBox-based uiBox, redux. This system of having one uiControl vtable to rule them all isn't going to work; each backend will need a wildly different implementation; oh well :/

redo/unix/box.c

@@ -0,0 +1,159 @@
+// 7 april 2015
+#include "out/ui.h"
+#include "uipriv.h"
+
+struct box {
+	uiBox b;
+	GtkWidget *widget;
+	GtkContainer *container;
+	GtkBox *box;
+	void (*baseCommitDestroy)(uiControl *);
+	struct ptrArray *controls;		// TODO switch to GArray
+	int vertical;
+	int padded;
+	GtkSizeGroup *stretchygroup;		// ensures all stretchy controls have the same size
+};
+
+struct boxControl {
+	uiControl *c;
+	int stretchy;
+};
+
+uiDefineControlType(uiBox, uiTypeBox, struct box)
+
+static void boxCommitDestroy(uiControl *c)
+{
+	struct box *b = (struct box *) c;
+	struct boxControl *bc;
+
+	// don't chain up to base here; we need to destroy children ourselves first
+	while (b->controls->len != 0) {
+		bc = ptrArrayIndex(b->controls, struct boxControl *, 0);
+		uiControlSetParent(bc->c, NULL);
+		uiControlDestroy(bc->c);
+		ptrArrayDelete(b->controls, 0);
+		uiFree(bc);
+	}
+	ptrArrayDestroy(b->controls);
+	// kill the size group
+	g_object_unref(b->stretchygroup);
+	// NOW we can chain up to base
+	(*(b->baseCommitDestroy))(uiControl(b));
+}
+
+static uintptr_t boxHandle(uiControl *c)
+{
+	struct box *b = (struct box *) c;
+
+	return (uintptr_t) (b->widget);
+}
+
+static void boxContainerUpdateState(uiControl *c)
+{
+	struct box *b = (struct box *) c;
+	struct boxControl *bc;
+	uintmax_t i;
+
+	for (i = 0; i < b->controls->len; i++) {
+		bc = ptrArrayIndex(b->controls, struct boxControl *, i);
+		uiControlUpdateState(bc->c);
+	}
+}
+
+static void boxAppend(uiBox *ss, uiControl *c, int stretchy)
+{
+	struct box *b = (struct box *) ss;
+	struct boxControl *bc;
+	uintmax_t i;
+
+	bc = uiNew(struct boxControl);
+	bc->c = c;
+	bc->stretchy = stretchy;
+	uiControlSetParent(bc->c, uiControl(b));
+	if (bc->stretchy)
+		gtk_size_group_add_widget(b->stretchygroup, GTK_WIDGET(uiControlHandle(bc->c)));
+	ptrArrayAppend(b->controls, bc);
+	uiControlQueueResize(uiControl(b));
+}
+
+static void boxDelete(uiBox *ss, uintmax_t index)
+{
+	struct box *b = (struct box *) ss;
+	struct boxControl *bc;
+
+	bc = ptrArrayIndex(b->controls, struct boxControl *, index);
+	ptrArrayDelete(b->controls, index);
+	if (bc->stretchy)
+		gtk_size_group_remove_widget(b->stretchygroup, GTK_WIDGET(uiControlHandle(bc->c)));
+	uiControlSetParent(bc->c, NULL);
+	uiFree(bc);
+	uiControlQueueResize(uiControl(b));
+}
+
+static int boxPadded(uiBox *ss)
+{
+	struct box *b = (struct box *) ss;
+
+	return b->padded;
+}
+
+static void boxSetPadded(uiBox *ss, int padded)
+{
+	struct box *b = (struct box *) ss;
+
+	b->padded = padded;
+	if (b->padded)
+		if (b->vertical)
+			gtk_box_set_spacing(b->box, gtkYPadding);
+		else
+			gtk_box_set_spacing(b->box, gtkXPadding);
+	else
+		gtk_box_set_spacing(b->box, 0);
+	uiControlQueueResize(uiControl(b));
+}
+
+static uiBox *finishNewBox(GtkOrientationType orientation)
+{
+	struct box *b;
+
+	b = (struct box *) uiNewControl(uiTypeBox());
+
+	b->widget = gtk_box_new(orientation, 0);
+	b->container = GTK_CONTAINER(b->widget);
+	b->box = GTK_BOX(b->widget);
+
+	b->vertical = orientation == GTK_ORIENTATION_VERTICAL;
+
+	if (b->vertical)
+		b->stretchygroup = gtk_size_group_new(GTK_SIZE_GROUP_VERTICAL);
+	else
+		b->stretchygroup = gtk_size_group_new(GTK_SIZE_GROUP_HORIZONTAL);
+
+	b->controls = newPtrArray();
+
+	uiControl(b)->Handle = boxHandle;
+	uiControl(b)->PreferredSize = boxPreferredSize;
+	b->baseResize = uiControl(b)->Resize;
+	uiControl(b)->Resize = boxResize;
+	uiControl(b)->HasTabStops = boxHasTabStops;
+	b->baseCommitDestroy = uiControl(b)->CommitDestroy;
+	uiControl(b)->CommitDestroy = boxCommitDestroy;
+	uiControl(b)->ContainerUpdateState = boxContainerUpdateState;
+
+	uiBox(b)->Append = boxAppend;
+	uiBox(b)->Delete = boxDelete;
+	uiBox(b)->Padded = boxPadded;
+	uiBox(b)->SetPadded = boxSetPadded;
+
+	return uiBox(b);
+}
+
+uiBox *uiNewHorizontalBox(void)
+{
+	return finishNewBox(GTK_ORIENTATION_HORIZONTAL);
+}
+
+uiBox *uiNewVerticalBox(void)
+{
+	return finishNewBox(GTK_ORIENTATION_VERTICAL);
+}