keyboard: add an on-screen keyboard

https://bugzilla.gnome.org/show_bug.cgi?id=612662

data/org.gnome.shell.gschema.xml.in

@@ -53,6 +53,7 @@
     <child name="clock" schema="org.gnome.shell.clock"/>
     <child name="calendar" schema="org.gnome.shell.calendar"/>
     <child name="recorder" schema="org.gnome.shell.recorder"/>
+    <child name="keyboard" schema="org.gnome.shell.keyboard"/>
   </schema>
 
   <schema id="org.gnome.shell.calendar" path="/org/gnome/shell/calendar/"
@@ -66,6 +67,24 @@
       </key>
   </schema>
 
+  <schema id="org.gnome.shell.keyboard" path="/org/gnome/shell/keyboard/"
+          gettext-domain="@GETTEXT_PACKAGE@">
+    <key name="show-keyboard" type="b">
+      <default>false</default>
+      <_summary>Show the onscreen keyboard</_summary>
+      <_description>
+        If true, display onscreen keyboard.
+      </_description>
+    </key>
+    <key name="keyboard-type" type="s">
+      <default>'touch'</default>
+      <_summary>Which keyboard to use</_summary>
+      <_description>
+        The type of keyboard to use.
+      </_description>
+    </key>
+  </schema>
+
   <schema id="org.gnome.shell.clock" path="/org/gnome/shell/clock/"
           gettext-domain="@GETTEXT_PACKAGE@">
     <key name="show-seconds" type="b">

data/theme/gnome-shell.css

@@ -1849,3 +1849,58 @@ StTooltip StLabel {
 .magnifier-zoom-region.full-screen {
     border-width: 0px;
 }
+
+/* On-screen Keyboard */
+
+#keyboard {
+    background: rgba(0,0,0,0.8);
+}
+
+.keyboard-layout {
+    spacing: 10px;
+    padding: 10px;
+}
+
+.keyboard-row {
+    spacing: 15px;
+}
+
+.keyboard-key {
+    min-height: 30px;
+    min-width: 30px;
+    background-gradient-start: rgba(255,245,245,0.4);
+    background-gradient-end: rgba(105,105,105,0.1);
+    background-gradient-direction: vertical;
+    font-size: 14pt;
+    font-weight: bold;
+    border-radius: 10px;
+    border: 2px solid #a0a0a0;
+    color: white;
+}
+
+.keyboard-key:grayed {
+   color: #808080;
+   border-color: #808080;
+}
+
+.keyboard-key:checked,
+.keyboard-key:hover {
+    background: #303030;
+    border: 3px solid white;
+}
+
+.keyboard-key:active {
+    background: #808080;
+}
+
+.keyboard-subkeys {
+    color: white;
+    padding: 5px;
+    -arrow-border-radius: 10px;
+    -arrow-background-color: #090909;
+    -arrow-border-width: 2px;
+    -arrow-border-color: white;
+    -arrow-base: 20px;
+    -arrow-rise: 10px;
+    -boxpointer-gap: 5px;
+}