replace deprecated classes, update code, fix errors, add missing stuff

resources/ui/create-category.blp

@@ -0,0 +1,20 @@
+using Gtk 4.0;
+using Adw 1;
+
+template $FlashcardsCreateCategoryDialog : Adw.AlertDialog {
+  heading: "Create a new category";
+  default-response: "add";
+  close-response: "cancel";
+  responses [
+    cancel: _("Cancel"),
+    add: _("Add") suggested,
+  ]
+  response => $on_response();
+
+  Adw.EntryRow entry {
+    title: "Category name";
+    styles [
+      "card",
+    ]
+  }
+}

resources/ui/meson.build

@@ -0,0 +1,8 @@
+blueprints = custom_target('blueprints',
+  input: files(
+    'window.blp',
+    'create-category.blp'
+  ),
+  output: '.',
+  command: [find_program('blueprint-compiler'), 'batch-compile', '@OUTPUT@', '@CURRENT_SOURCE_DIR@', '@INPUT@'],
+)

resources/ui/window.blp

@@ -0,0 +1,100 @@
+using Gtk 4.0;
+using Adw 1;
+
+template $FlashcardsAppWindow : Adw.ApplicationWindow {
+  title: _("Flashcards");
+
+  Adw.Breakpoint {
+    condition ( "max-width: 400sp" )
+    setters {
+      split_view.collapsed: true;
+    }
+  }
+
+  Adw.NavigationSplitView split_view {
+    [sidebar]
+    Adw.NavigationPage sidebar{
+      title: _("Categories");
+
+      Box {
+        orientation: vertical;
+        hexpand: true;
+        width-request: 360;
+
+        Adw.HeaderBar {
+          [end]
+          Gtk.Button {
+            icon-name: "list-add-symbolic";
+            clicked => $on_add_category();
+          }
+        }
+
+        Adw.Clamp {
+          hexpand: true;
+          
+          ListBox topics {
+            hexpand: true;
+            selection-mode: single;
+            margin-top: 12;
+            margin-bottom: 12;
+            margin-start: 12;
+            margin-end: 12;
+            row-selected => $on_category_selected();
+
+            styles [
+              "boxed-list",
+            ]
+          }
+        }
+      }
+    }
+
+    [content]
+    Adw.NavigationPage content {
+      title: _("Flashcards");
+      Box {
+        orientation: vertical;
+        hexpand: true;
+
+        Adw.HeaderBar {
+          [end]
+          Gtk.MenuButton {
+            icon-name: "open-menu-symbolic";
+            menu-model: primary_menu;
+          }
+        }
+
+        Adw.Clamp {
+          hexpand: true;
+          child: Adw.Bin {
+            margin-top: 12;
+            margin-bottom: 12;
+            margin-start: 12;
+            margin-end: 12;
+
+            styles [
+              "card",
+            ]
+            child: Label {
+              margin-top: 24;
+              margin-bottom: 24;
+              margin-start: 24;
+              margin-end: 24;
+              wrap: true;
+              label: "Wie viel Grad hat ein Kreis?";
+            };
+          };
+        }
+      }
+    }
+  }
+}
+
+menu primary_menu {
+  section {
+    item {
+    	label: _("About Flashcards");
+      action: "app.about";
+    }
+  }
+}