Added signals slot to block scenegraph updates

Status Job ID Name Coverage
  Test
passed #1394
Linux
clang-c++11-Qt4

00:35:03

passed #1398
Linux
clang-c++11-Qt5

00:47:50

passed #1396
Linux
clang-c++98-Qt4

00:25:10

passed #1400
Linux
clang-c++98-Qt5

00:37:19

passed #1393
Linux
gcc-c++11-Qt4

00:55:16

passed #1397
Linux
gcc-c++11-Qt5

00:56:03

passed #1395
Linux
gcc-c++98-Qt4

00:37:31

passed #1399
Linux
gcc-c++98-Qt5

00:42:57