change text on message.ui from "Copy to Clipboard" to "Copy Signature" and

add an Alt-Shortcut to "Clear &All"

src/qt/forms/messagepage.ui

@@ -131,7 +131,7 @@
         <string>Copy the current signature to the system clipboard</string>
        </property>
        <property name="text">
-        <string>&amp;Copy to Clipboard</string>
+        <string>&amp;Copy Signature</string>
        </property>
        <property name="icon">
         <iconset resource="../bitcoin.qrc">
@@ -145,7 +145,7 @@
         <string>Reset all sign message fields</string>
        </property>
        <property name="text">
-        <string>Clear all</string>
+        <string>Clear &amp;All</string>
        </property>
        <property name="icon">
         <iconset resource="../bitcoin.qrc">