New tabs always open below dialogs, never above.

This fixes the bug that tabs opened with -remote used to hide existing
dialogs, which then became unusable until the new tabs were closed.

src/terminal/tab.c (init_tab): Put the new tab immediately above
existing ones, or if it's the first one, then at the bottom of the stack.
Added assertions.

src/terminal/terminal.h (struct terminal): Redocumented the stacking
order of windows.

src/terminal/window.c [CONFIG_DEBUG] (assert_window_stacking): New function.

src/terminal/window.h (assert_window_stacking): New function or no-op macro.

src/terminal/tab.c

@@ -30,6 +30,7 @@ struct window *
 init_tab(struct terminal *term, void *data, window_handler_T handler)
 {
 	struct window *win = mem_calloc(1, sizeof(*win));
+	struct window *pos;
 
 	if (!win) return NULL;
 
@@ -39,7 +40,21 @@ init_tab(struct terminal *term, void *data, window_handler_T handler)
 	win->type = WINDOW_TAB;
 	win->resize = 1;
 
-	add_to_list(term->windows, win);
+	/* Insert the new tab immediately above all existing tabs in
+	 * the stack of windows.  */
+	foreach_tab (pos, term->windows) {
+		pos = pos->prev;
+		goto found_pos;
+	}
+	/* This is a new terminal and there are no tabs yet.  If there
+	 * were a main menu already, then we'd have to place the tab
+	 * above it if it were inactive, or below if it were active.  */
+	assert(term->main_menu == NULL);
+	pos = (struct window *) term->windows.prev;
+ found_pos:
+	add_at_pos(pos, win);
+
+	assert_window_stacking(term);
 
 	return win;
 }

src/terminal/terminal.h

@@ -69,13 +69,26 @@ struct terminal {
 	 * are sure what are you doing) to make sure that you don't distribute
 	 * events etc to inactive tabs.
 	 *
-	 * The stack is top-down, thus .next is the stack's top, the current
-	 * window. .prev is the first tab.
+	 * The stack is top-down, thus .next is the stack's top, the
+	 * current window; and .prev is the bottom, covered by others.
+	 * - Dialogs or active menus are at the top.
+	 * - Next come all tabs (window.type == WINDOW_TAB).  The tab
+	 *   created last is at the top, and the tab created first is
+	 *   at the bottom; but current_tab controls which tab is
+	 *   actually displayed.
+	 * - If the main menu is inactive, then it is at the very bottom,
+	 *   hidden under the tabs.
+	 * Call assert_window_stacking to verify this.
 	 *
 	 * FIXME: Tabs violate the stack nature of this list, they appear there
 	 * randomly but always in the order in which they were inserted there.
 	 * Eventually, they should all live at the stack bottom, with the
-	 * actual tab living on the VERY bottom. --pasky */
+	 * actual tab living on the VERY bottom. --pasky
+	 *
+	 *   Keeping the current tab at the very bottom would require storing
+	 *   tab numbers explicitly, rather than computing them from the
+	 *   stack order as is done now.  Also, what should be done with the
+	 *   inactive main menu?  --KON */
 	struct list_head windows; /* {struct window} */
 
 	/* The specification of terminal in terms of terminal options. */

src/terminal/window.c

@@ -6,6 +6,7 @@
 
 #include "elinks.h"
 
+#include "bfu/menu.h"
 #include "terminal/event.h"
 #include "terminal/tab.h"
 #include "terminal/terminal.h"
@@ -171,3 +172,25 @@ add_empty_window(struct terminal *term, void (*fn)(void *), void *data)
 	ewd->called_once = 0;
 	add_window(term, empty_window_handler, ewd);
 }
+
+#if CONFIG_DEBUG
+/* Check that term->windows are in the documented order.  */
+void
+assert_window_stacking(struct terminal *term)
+{
+	int prev_type = WINDOW_NORMAL;
+	const struct window *win;
+	const struct window *main_menu_win;
+
+	/* The main menu can be either above or below the tabs.  */
+	main_menu_win = term->main_menu ? term->main_menu->win : NULL;
+
+	foreach (win, term->windows) {
+		if (win != main_menu_win) {
+			if (prev_type == WINDOW_TAB)
+				assert(win->type == WINDOW_TAB);
+			prev_type = win->type;
+		}
+	}
+}
+#endif	/* CONFIG_DEBUG */

src/terminal/window.h

@@ -56,4 +56,10 @@ void get_parent_ptr(struct window *, int *, int *);
 
 void add_empty_window(struct terminal *, void (*)(void *), void *);
 
+#if CONFIG_DEBUG
+void assert_window_stacking(struct terminal *);
+#else
+#define assert_window_stacking(t) ((void) (t))
+#endif
+
 #endif