Refactored mainwindow source, columns size and pos remembering.

Refactored MainWindow source, splitted initialization and
helper functions into separate files.

Now lists headers sizes and positions are remembered and correctly
restored on launch.

ui/mainwindow_helpers.go

@@ -0,0 +1,35 @@
+package ui
+
+import (
+    // stdlib
+    "strings"
+
+    // other
+    "github.com/mattn/go-gtk/glib"
+    "github.com/mattn/go-gtk/gtk"
+)
+
+func (m *MainWindow) getIpFromServersList(current_tab string) string {
+    // Getting server's address from list.
+    sel := m.all_servers.GetSelection()
+    model := m.all_servers.GetModel()
+    iter := new(gtk.TreeIter)
+    _ = sel.GetSelected(iter)
+
+    // Getting server address.
+    var srv_addr string
+    srv_addr_gval := glib.ValueFromNative(srv_addr)
+    model.GetValue(iter, m.column_pos["Servers"]["IP"], srv_addr_gval)
+
+    if strings.Contains(current_tab, "Favorites") {
+        // Getting server's address from list.
+        sel = m.fav_servers.GetSelection()
+        model = m.fav_servers.GetModel()
+        iter := new(gtk.TreeIter)
+        _ = sel.GetSelected(iter)
+        model.GetValue(iter, m.column_pos["Favorites"]["IP"], srv_addr_gval)
+    }
+    server_address := srv_addr_gval.GetString()
+
+    return server_address
+}