flush Stage>>keysPressed when prompting the user

history.txt

@@ -2480,3 +2480,7 @@ ______
 150325
 ------
 * Threads: fixed #752
+
+150415
+------
+* Threads: flush Stage>>keysPressed when prompting the user

threads.js

@@ -83,7 +83,7 @@ ArgLabelMorph, localize, XML_Element, hex_sha512*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.threads = '2015-March-25';
+modules.threads = '2015-April-15';
 
 var ThreadManager;
 var Process;
@@ -1816,6 +1816,7 @@ Process.prototype.doAsk = function (data) {
         isStage = this.blockReceiver() instanceof StageMorph,
         activePrompter;
 
+    stage.keysPressed = {};
     if (!this.prompter) {
         activePrompter = detect(
             stage.children,