gtk: start a custom Console widget

qemu-gtk4/data/resources.gresource.xml

@@ -2,6 +2,7 @@
 <gresources>
   <gresource prefix="/org/qemu/gtk4/">
     <file compressed="true" preprocess="xml-stripblanks" alias="shortcuts.ui">resources/ui/shortcuts.ui</file>
+    <file compressed="true" preprocess="xml-stripblanks" alias="console.ui">resources/ui/console.ui</file>
     <file compressed="true" preprocess="xml-stripblanks" alias="window.ui">resources/ui/window.ui</file>
 
     <file compressed="true" alias="style.css">resources/style.css</file>

qemu-gtk4/data/resources/ui/console.ui

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <template class="QemuConsole" parent="GtkWidget">
+    <property name="layout-manager">
+      <object class="GtkBinLayout"/>
+    </property>
+    <child>
+      <object class="GtkNotebook">
+        <child>
+          <object class="GtkGLArea" id="glarea"/>
+        </child>
+        <child type="tab">
+          <object class="GtkLabel" id="notebook-tab">
+            <property name="label">Console</property>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel" id="label">
+            <property name="label" translatable="yes">Hello world2!</property>
+          </object>
+        </child>
+        <child type="tab">
+          <object class="GtkLabel" id="notebook-tab2">
+            <property name="label">Tab2</property>
+          </object>
+        </child>
+      </object>
+    </child>
+  </template>
+</interface>

qemu-gtk4/data/resources/ui/window.ui

@@ -1,3 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
 <interface>
   <menu id="primary_menu">
     <section>
@@ -29,11 +30,7 @@
       </object>
     </child>
     <child>
-      <object class="GtkLabel" id="label">
-        <property name="label" translatable="yes">Hello world!</property>
-        <style>
-          <class name="title-header"/>
-        </style>
+      <object class="QemuConsole" id="console">
       </object>
     </child>
   </template>