Add option to sync files in new profile assistant

GTK file chooser allows selecting either files or directories but not
both. File choosers in the new profile assistant were configured for
selecting directories, with the expectation that this covers the vast
majority of usages. This patch adds an option for the user to choose
files instead of directories, enabling specifying single files as sync
roots.

src/uigtk3.ml

@@ -1407,58 +1407,113 @@ let createProfile parent =
 
   (* Directory selection *)
   let directorySelection = GPack.vbox ~border_width:12 ~spacing:6 () in
+  let dirhb = GPack.hbox ~packing:(directorySelection#pack ~expand:false) () in
+  adjustSize
+    (GMisc.label ~xalign:0. ~line_wrap:false ~justify:`LEFT
+       ~text:"Please select the two "
+       ~packing:(dirhb#pack ~expand:false) ());
+  let dirKindCombo =
+    GEdit.combo_box_text
+      ~strings:["directories"; "files"]
+      ~active:0 ~packing:(dirhb#pack ~expand:false) () in
+  let dirKind =
+    GtkReact.text_combo dirKindCombo
+      >> fun i -> List.nth [`Dir; `File] i
+  in
   adjustSize
     (GMisc.label ~xalign:0. ~line_wrap:true ~justify:`LEFT
-       ~text:"Please select the two directories that you want to synchronize."
-       ~packing:(directorySelection#pack ~expand:false) ());
+       ~text:" that you want to synchronize."
+       ~packing:(dirhb#pack ~expand:false) ());
+  (* Not sure what's going on here, but when setting the focus on an element,
+     it's actually the next element that gets the focus by default. We want
+     the focus to be on the first directory selector. Setting the focus on the
+     combo here achieves exactly that... *)
+  ignore ((fst dirKindCombo)#misc#connect#map ~callback:(fst dirKindCombo)#misc#grab_focus);
   let secondDirLabel1 =
     GMisc.label ~xalign:0. ~line_wrap:true ~justify:`LEFT
-      ~text:"The second directory is relative to your home \
-             directory on the remote machine."
+      ~text:""
       ~packing:(directorySelection#pack ~expand:false) ()
   in
   adjustSize secondDirLabel1;
   GtkReact.show secondDirLabel1 ((React.lift2 (||) isLocal isSocket) >> not);
+  GtkReact.label secondDirLabel1 (dirKind >> function
+    | `Dir  -> "The second directory is relative to your home \
+                directory on the remote machine."
+    | `File -> "The second file is relative to your home \
+                directory on the remote machine.");
   let secondDirLabel2 =
     GMisc.label ~xalign:0. ~line_wrap:true ~justify:`LEFT
-      ~text:"The second directory is relative to \
-             the working directory of the Unison server \
-             running on the remote machine."
+      ~text:""
       ~packing:(directorySelection#pack ~expand:false) ()
   in
   adjustSize secondDirLabel2;
   GtkReact.show secondDirLabel2 isSocket;
+  GtkReact.label secondDirLabel2 (dirKind >> function
+    | `Dir  -> "The second directory is relative to \
+                the working directory of the Unison server \
+                running on the remote machine."
+    | `File -> "The second file is relative to \
+                the working directory of the Unison server \
+                running on the remote machine.");
   let tbl =
     let al =
       GBin.alignment ~packing:(directorySelection#pack ~expand:false) () in
     al#set_left_padding 12;
     GPack.table ~rows:2 ~columns:2 ~col_spacings:12 ~row_spacings:6
       ~packing:(al#add) () in
-(*XXX Should focus on this button when becomes visible... *)
   let firstDirButton =
     GFile.chooser_button ~action:`SELECT_FOLDER ~title:"First Directory"
        ~packing:(tbl#attach ~left:1 ~top:0 ~expand:`X) ()
   in
-  isLocal >| (fun b -> firstDirButton#set_title
-                         (if b then "First Directory" else "Local Directory"));
+  React.lift2
+    (fun local dirkind ->
+      firstDirButton#set_action (
+        match dirkind with
+        | `Dir  -> `SELECT_FOLDER
+        | `File -> `OPEN
+      );
+      firstDirButton#set_title (
+        match local, dirkind with
+        | true, `Dir   -> "First Directory"
+        | false, `Dir  -> "Local Directory"
+        | true, `File  -> "First File"
+        | false, `File -> "Local File"
+      )
+    ) isLocal dirKind |> ignore;
+
   GtkReact.label_underlined
     (GMisc.label ~xalign:0.
        ~mnemonic_widget:firstDirButton
        ~packing:(tbl#attach ~left:0 ~top:0 ~expand:`NONE) ())
-    (isLocal >> fun b ->
-       if b then "_First directory:" else "_Local directory:");
+    (React.lift2 (fun local dirkind ->
+        match local, dirkind with
+        | true, `Dir -> "_First directory:"
+        | false, `Dir -> "_Local directory:"
+        | true, `File -> "_First file:"
+        | false, `File -> "_Local file:"
+      ) isLocal dirKind);
   let noneToEmpty o = match o with None -> "" | Some s -> s in
   let firstDir = GtkReact.file_chooser firstDirButton >> noneToEmpty in
+
   let secondDirButton =
     GFile.chooser_button ~action:`SELECT_FOLDER ~title:"Second Directory"
        ~packing:(tbl#attach ~left:1 ~top:1 ~expand:`X) () in
+  dirKind >| (function
+    | `Dir  -> secondDirButton#set_action `SELECT_FOLDER;
+               secondDirButton#set_title "Second Directory"
+    | `File -> secondDirButton#set_action `OPEN;
+               secondDirButton#set_title "Second File"
+  );
+
   let secondDirLabel =
     GMisc.label ~xalign:0.
       ~text:"Se_cond directory:"
       ~use_underline:true ~mnemonic_widget:secondDirButton
       ~packing:(tbl#attach ~left:0 ~top:1 ~expand:`NONE) () in
   GtkReact.show secondDirButton isLocal;
   GtkReact.show secondDirLabel isLocal;
+  GtkReact.label_underlined secondDirLabel
+    (dirKind >> function `Dir -> "Se_cond directory:" | `File -> "Se_cond file:");
   let remoteDirEdit =
     GEdit.entry ~packing:(tbl#attach ~left:1 ~top:1 ~expand:`X) ()
   in
@@ -1470,19 +1525,13 @@ let createProfile parent =
   in
   GtkReact.show remoteDirEdit (isLocal >> not);
   GtkReact.show remoteDirLabel (isLocal >> not);
+  GtkReact.label_underlined remoteDirLabel
+    (dirKind >> function `Dir -> "_Remote directory:" | `File -> "_Remote file:");
   let secondDir =
     React.lift3 (fun b l r -> if b then l else r) isLocal
       (GtkReact.file_chooser secondDirButton >> noneToEmpty)
       (GtkReact.entry remoteDirEdit)
   in
-  let dirExplanationLabel =
-    GMisc.label ~xalign:0. ~line_wrap:true ~justify:`LEFT
-      ~text:"Note: To synchronize a single file with another file, you \
-             currently have to create the profile manually or specify the \
-             files on the command line."
-      ~packing:(directorySelection#pack ~expand:false) ()
-  in
-  dirExplanationLabel#set_max_width_chars 80;
   ignore
     (assistant#append_page
        ~title:"Directory Selection"