The "Select Destination Directory" dialog didn't ask for confirmation

about installing into a pre-existing directory *unless* you hit the
Browse button first.  At least while testing, this screwed me repeatedly.
Plus I really liked the Inno Setup scheme of giving you a list box in
its "select directory" dialog without needing a distinct browse button
to ask for that.

So I redid this dialog from scratch:  now gives a list box at once, the
browse button is gone, it asks for confirmation if the directory already
exists, and, since this is the first dialog in the set now, also removed
its "Back" button.

PCbuild/python20.wse

@@ -310,18 +310,6 @@ item: Custom Dialog Set
       Text Spanish=&Siguiente >
       Text Italian=&Avanti >
     end
-    item: Push Button
-      Rectangle=105 187 150 202
-      Variable=DIRECTION
-      Value=B
-      Create Flags=01010000000000010000000000000000
-      Flags=0000000000000001
-      Text=< &Back
-      Text French=< &Retour
-      Text German=< &Zurück
-      Text Spanish=< &Atrás
-      Text Italian=< &Indietro
-    end
     item: Push Button
       Rectangle=211 187 256 202
       Action=3
@@ -338,7 +326,7 @@ item: Custom Dialog Set
       Create Flags=01010000000000000000000000000111
     end
     item: Static
-      Rectangle=86 8 258 42
+      Rectangle=85 1 257 26
       Create Flags=01010000000000000000000000000000
       Flags=0000000000000001
       Name=Times New Roman
@@ -349,41 +337,20 @@ item: Custom Dialog Set
       Text Spanish=Seleccione el directorio de destino
       Text Italian=Selezionare Directory di destinazione
     end
-    item: Static
-      Rectangle=86 42 256 82
-      Create Flags=01010000000000000000000000000000
-      Text=Please select the directory where the %APPTITLE% files are to be installed.
-      Text French=Veuillez sélectionner le répertoire dans lequel les fichiers %APPTITLE% doivent être installés.
-      Text German=Geben Sie an, in welchem Verzeichnis die %APPTITLE%-Dateien installiert werden sollen.
-      Text Spanish=Por favor seleccione el directorio donde desee instalar los archivos de %APPTITLE%.
-      Text Italian=Selezionare la directory dove verranno installati i file %APPTITLE%.
-    end
-    item: Static
-      Rectangle=86 98 256 125
-      Action=1
-      Create Flags=01010000000000000000000000000111
-    end
-    item: Push Button
-      Rectangle=208 106 253 121
-      Variable=MAINDIR_SAVE
-      Value=%MAINDIR%
-      Destination Dialog=1
-      Action=2
-      Create Flags=01010000000000010000000000000000
-      Text=Browse
-      Text French=Parcourir
-      Text German=Durchsuchen
-      Text Spanish=Buscar
-      Text Italian=Sfoglie
-    end
-    item: Static
-      Rectangle=90 109 206 120
-      Create Flags=01010000000000000000000000000000
+    item: Listbox
+      Rectangle=85 38 256 178
+      Variable=MAINDIR
+      Enabled Color=00000000000000001111111111111111
+      Create Flags=01010000100000010000000101000001
+      Flags=0000110000001010
       Text=%MAINDIR%
-      Text French=%MAINDIR%
-      Text German=%MAINDIR%
-      Text Spanish=%MAINDIR%
-      Text Italian=%MAINDIR%
+      Text=
+    end
+    item: Static
+      Rectangle=95 22 259 37
+      Enabled Color=00000000000000001111111111111111
+      Create Flags=01010000000000000000000000000000
+      Text=Please select a directory for the %APPTITLE% files.
     end
   end
   item: Dialog