Decided what to do about menuless menubars and implemented it.

TODO.md

@@ -16,7 +16,6 @@ ultimately:
 			- in which case, hide leading or trailing separators?
 - generate libui.lib and related files
 - make OS-specific headers generated by an IDL
-- figure out what to do on Windows and GTK+ if we don't have menus but the user wants a menubar (zero-height widget? don't bother? complain?)
 - bin.c
 	- find a way to move the has parent check at the beginning of binDestroy()
 - menu item state change while the menu is visible (not in response to user action)
@@ -41,3 +40,4 @@ notes to self
 - note that uiInitOptions should be initialized to zero
 - explicitly document that uiCheckboxSetChecked() and uiEntrySetText() do not fire uiCheckboxOnToggled() and uiEntryOnChanged(), respectively
 - note that uiControlResize() on a uiContainer also updates
+- note that if a menu is requested on systems with menubars on windows but no menus are defined, the result is a blank menubar, with whatever that means left up to the OS to decide

unix/menu.c

@@ -297,6 +297,7 @@ GtkWidget *makeMenubar(uiWindow *w)
 
 	menubar = gtk_menu_bar_new();
 
+	if (menus != NULL)
 		for (i = 0; i < menus->len; i++) {
 			m = g_array_index(menus, struct menu *, i);
 			menuitem = gtk_menu_item_new_with_label(m->name);