Fixes segfault after switch panel mode

...from non-listing one (info, tree, quick view) to panelization.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>

src/filemanager/panelize.c

@@ -52,6 +52,7 @@
 
 #include "dir.h"
 #include "midnight.h"           /* current_panel */
+#include "panel.h"              /* WPanel */
 
 #include "panelize.h"
 
@@ -484,9 +485,10 @@ panelize_save_panel (struct WPanel *panel)
 void
 cd_panelize_cmd (void)
 {
-    WPanel *panel = MENU_PANEL_IDX == 0 ? left_panel : right_panel;
+    if (get_display_type (MENU_PANEL_IDX) != view_listing)
+        set_display_type (MENU_PANEL_IDX, view_listing);
 
-    do_panelize_cd (panel);
+    do_panelize_cd ((struct WPanel *) get_panel_widget (MENU_PANEL_IDX));
 }
 
 /* --------------------------------------------------------------------------------------------- */

src/filemanager/panelize.h

@@ -11,6 +11,8 @@
 
 /*** structures declarations (and typedefs of structures)*****************************************/
 
+struct WPanel;
+
 /*** global variables defined in .c file *********************************************************/
 
 /*** declarations of public functions ************************************************************/