Mcdu: add margin and make all keys same size

src/ui/app.rs

@@ -54,7 +54,9 @@ impl AsyncComponent for AppModel {
                             set_hexpand: true,
                     },
                 },
-                model.mcdu.widget(),
+                model.mcdu.widget() {
+                    set_margin_all: 10,
+                },
             }
         }
     }

src/ui/mcdu.rs

@@ -50,6 +50,8 @@ impl SimpleComponent for McduModel {
             },
             #[name = "keyboard"]
             gtk::Grid {
+                set_column_homogeneous: true,
+                set_row_homogeneous: true,
                 set_column_spacing: 5,
                 set_row_spacing: 5,
             }