From a05bb5023043b08f0d4508a634f1527e6e653d7f Mon Sep 17 00:00:00 2001
From: Daniel Imms <daimms@microsoft.com>
Date: Sun, 15 Jan 2017 21:41:42 -0800
Subject: [PATCH] Don't drop selection on modifier keyup

Fixes #348
---
 src/xterm.js | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/xterm.js b/src/xterm.js
index 6649a0333f..ed415b319d 100644
--- a/src/xterm.js
+++ b/src/xterm.js
@@ -525,7 +525,11 @@ Terminal.bindKeys = function(term) {
     term.keyPress(ev);
   }, true);
 
-  on(term.element, 'keyup', term.focus.bind(term));
+  on(term.element, 'keyup', function(ev) {
+    if (!wasMondifierKeyOnlyEvent(ev)) {
+      term.focus(term);
+    }
+  }, true);
 
   on(term.textarea, 'keydown', function(ev) {
     term.keyDown(ev);
@@ -4984,6 +4988,12 @@ Terminal.prototype.deleteColumns = function() {
   this.maxRange();
 };
 
+function wasMondifierKeyOnlyEvent(ev) {
+  return ev.keyCode === 16 || // Shift
+    ev.keyCode === 17 || // Ctrl
+    ev.keyCode === 18; // Alt
+}
+
 /**
  * Character Sets
  */