Avoid scrolling on RFB object focus

Chrome scrolls the view to show as much as possible of the canvas when
we call focus(), which is likely not the desired behaviour.

This also exposes the ability to pass on future options when focusing
the RFB object manually.

3 files changed, 18 insertions, 4 deletions

diff --git a/core/rfb.js b/core/rfb.js
index ea3bf58..084a457 100644
--- a/core/rfb.js
+++ b/core/rfb.js
@@ -432,8 +432,8 @@ export default class RFB extends EventTargetMixin {
         }
     }
 
-    focus() {
-        this._canvas.focus();
+    focus(options) {
+        this._canvas.focus(options);
     }
 
     blur() {
@@ -609,7 +609,7 @@ export default class RFB extends EventTargetMixin {
             return;
         }
 
-        this.focus();
+        this.focus({ preventScroll: true });
     }
 
     _setDesktopName(name) {
diff --git a/docs/API.md b/docs/API.md
index aa5aea7..066e895 100644
--- a/docs/API.md
+++ b/docs/API.md
@@ -328,7 +328,14 @@ Keyboard events will be sent to the remote server after this point.
 
 ##### Syntax
 
-    RFB.focus( );
+    RFB.focus( [options] );
+
+###### Parameters
+
+**`options`** *Optional*
+  - A `object` providing options to control how the focus will be
+    performed. Please see [`HTMLElement.focus()`](https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/focus)
+    for available options.
 
 #### RFB.blur()
 
diff --git a/tests/test.rfb.js b/tests/test.rfb.js
index 5f50581..f70bc14 100644
--- a/tests/test.rfb.js
+++ b/tests/test.rfb.js
@@ -392,6 +392,13 @@ describe('Remote Frame Buffer Protocol Client', function () {
                 client.focus();
                 expect(client._canvas.focus).to.have.been.calledOnce;
             });
+
+            it('should include focus options', function () {
+                client._canvas.focus = sinon.spy();
+                client.focus({ foobar: 12, gazonk: true });
+                expect(client._canvas.focus).to.have.been.calledOnce;
+                expect(client._canvas.focus).to.have.been.calledWith({ foobar: 12, gazonk: true});
+            });
         });
 
         describe('#blur', function () {