🎉 Add a dialog to ask for support

resources/ui/adw/prefs.ui

@@ -37,6 +37,40 @@ SPDX-License-Identifier: GPL-3.0-or-later
     </style>
   </object>
 
+  <!-- This dialog is occasionaly shown to ask the user for support. -->
+  <object class="AdwMessageDialog" id="support-dialog">
+    <property name="heading">Do you want to support Burn-My-Windows?</property>
+    <property name="body">If only one out of ten users would support this project with 1$ / month, I could work full-time on open-source projects!</property>
+    <property name="default-response">later</property>
+    <property name="close-response">later</property>
+    <responses>
+      <response id="never" appearance="destructive">Do not show this again!</response>
+      <response id="later">Maybe later...</response>
+    </responses>
+    <property name="extra-child">
+      <object class="GtkBox">
+        <property name="orientation">vertical</property>
+        <child>
+          <object class="GtkLabel">
+            <property name="hexpand">true</property>
+            <property name="halign">start</property>
+            <property name="use-markup">true</property>
+            <property name="label">Support me on Ko-fi: &lt;a href='https://ko-fi.com/schneegans'&gt;https://ko-fi.com/schneegans&lt;/a&gt;</property>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="hexpand">true</property>
+            <property name="halign">start</property>
+            <property name="use-markup">true</property>
+            <property name="label">Support me on GitHub: &lt;a href='https://github.com/sponsors/schneegans'&gt;https://github.com/sponsors/schneegans&lt;/a&gt;</property>
+          </object>
+        </child>
+      </object>
+    </property>
+
+  </object>
+
   <object class="AdwFlap" id="profile-editor-flap">
     <property name="orientation">vertical</property>
     <property name="fold-threshold-policy">natural</property>