Merge branch 'master' of https://github.com/prusa3d/Slic3r into et_copy_and_paste

src/slic3r/GUI/GLCanvas3D.cpp

@@ -2204,6 +2204,9 @@ void GLCanvas3D::on_idle(wxIdleEvent& evt)
 
 void GLCanvas3D::on_char(wxKeyEvent& evt)
 {
+    if (!m_initialized)
+        return;
+
     // see include/wx/defs.h enum wxKeyCode
     int keyCode = evt.GetKeyCode();
     int ctrlMask = wxMOD_CONTROL;