DisplaySettings: Give the UI a facelift :^)

- Split the main UI into two tabs: "Background" and "Monitor".
- Use a GUI::IconView for selecting background pictures.
- Tweak layout, spacing, etc.

Base/home/anon/BackgroundSettings.gml

@@ -0,0 +1,65 @@
+@GUI::Widget {
+    fill_with_background_color: true
+
+    layout: @GUI::VerticalBoxLayout {
+        margins: [4, 4, 4, 4]
+    }
+
+    @DisplaySettings::MonitorWidget {
+        name: "monitor_widget"
+    }
+
+    @GUI::Widget {
+        shrink_to_fit: true
+        layout: @GUI::HorizontalBoxLayout
+
+        @GUI::Label {
+            text: "Wallpaper:"
+            text_alignment: "CenterLeft"
+            fixed_width: 70
+        }
+
+        @GUI::ComboBox {
+            name: "wallpaper_combo"
+        }
+
+        @GUI::Button {
+            name: "wallpaper_open_button"
+            tooltip: "Select wallpaper from file system."
+            button_style: "Coolbar"
+            fixed_width: 22
+            fixed_height: 22
+        }
+    }
+
+    @GUI::Widget {
+        shrink_to_fit: true
+        layout: @GUI::HorizontalBoxLayout
+
+        @GUI::Label {
+            text: "Modes:"
+            text_alignment: "CenterLeft"
+            fixed_width: 70
+        }
+
+        @GUI::ComboBox {
+            name: "mode_combo"
+        }
+    }
+
+    @GUI::Widget {
+        shrink_to_fit: true
+        layout: @GUI::HorizontalBoxLayout
+
+        @GUI::Label {
+            text: "Color:"
+            text_alignment: "CenterLeft"
+            fixed_width: 70
+        }
+
+        @GUI::ColorInput {
+            name: "color_input"
+            fixed_width: 90
+        }
+    }
+}