On "new script", with valid script on clipbard, just install it.

content/newscript.js

@@ -39,19 +39,8 @@ function doInstall() {
 
   // finish making the script object ready to install
   // (put this created script into a file -- only way to install it)
-  var scope = {};
-  Components.utils.import('resource://greasemonkey/remoteScript.js', scope);
-  var remoteScript = new scope.RemoteScript();
-  var tempFileName = scope.cleanFilename(script.name, 'gm_script') + '.user.js';
-  var tempFile = GM_util.getTempFile(remoteScript._tempDir, tempFileName);
-  GM_util.writeToFile(scriptSrc, tempFile, function() {
-    // install this script
-    remoteScript.setScript(script, tempFile);
-    remoteScript.install();
-    // and fire up the editor!
-    GM_util.openInEditor(script);
-
-    // persist namespace value
+  GM_util.installScriptFromSource(scriptSrc, function() {
+    // Persist namespace value.
     GM_prefRoot.setValue("newscript_namespace", script.namespace);
     // Now that async write is complete, close the window.
     close();

modules/util/installScriptFromSource.js

@@ -0,0 +1,20 @@
+Components.utils.import('resource://greasemonkey/parseScript.js');
+Components.utils.import('resource://greasemonkey/remoteScript.js');
+Components.utils.import('resource://greasemonkey/util.js');
+
+const EXPORTED_SYMBOLS = ['installScriptFromSource'];
+
+function installScriptFromSource(aSource, aCallback) {
+  var remoteScript = new RemoteScript();
+  var script = parse(aSource);
+  var tempFileName = cleanFilename(script.name, 'gm_script') + '.user.js';
+  var tempFile = GM_util.getTempFile(remoteScript._tempDir, tempFileName);
+  GM_util.writeToFile(aSource, tempFile, function() {
+    // install this script
+    remoteScript.setScript(script, tempFile);
+    remoteScript.install();
+    // and fire up the editor!
+    GM_util.openInEditor(script);
+  });
+  if (aCallback) aCallback();
+}

modules/util/newUserScript.js

@@ -1,10 +1,39 @@
+Components.utils.import('resource://greasemonkey/parseScript.js');
+Components.utils.import('resource://greasemonkey/util.js');
+
 const EXPORTED_SYMBOLS = ['newUserScript'];
 
-const ww = Components.classes["@mozilla.org/embedcomp/window-watcher;1"]
+const gClipboard = Components.classes["@mozilla.org/widget/clipboard;1"]
+.getService(Components.interfaces.nsIClipboard);
+const gWindowWatcher = Components
+    .classes["@mozilla.org/embedcomp/window-watcher;1"]
     .getService(Components.interfaces.nsIWindowWatcher);
 
 function newUserScript(aWin) {
-  ww.openWindow(aWin,
-      "chrome://greasemonkey/content/newscript.xul", null,
-      "chrome,dependent,centerscreen,resizable,dialog", null);
+  var clipText = '';
+  try {
+    var transferable = Components.classes["@mozilla.org/widget/transferable;1"]
+        .createInstance(Components.interfaces.nsITransferable);
+    transferable.addDataFlavor('text/unicode');
+    gClipboard.getData(transferable, gClipboard.kGlobalClipboard);
+    var str = new Object(), strLen = new Object();
+    transferable.getTransferData('text/unicode', str, strLen);
+    if (str) {
+      str = str.value.QueryInterface(Components.interfaces.nsISupportsString);
+      clipText = str.data.substring(0, strLen.value / 2);
+    }
+  } catch (e) {
+    dump('Error reading clipboard:\n' + e + '\n');
+  }
+
+  // If there is a valid script with metadata on the clipboard ...
+  if (clipText && extractMeta(clipText)) {
+    // ... just install it!
+    GM_util.installScriptFromSource(clipText);
+  } else {
+    // Otherwise do GUIfied script creation.
+    gWindowWatcher.openWindow(aWin,
+        "chrome://greasemonkey/content/newscript.xul", null,
+        "chrome,dependent,centerscreen,resizable,dialog", null);
+  }
 }