diff --git a/tests/gui/abstract-tangible-test.cpp b/tests/gui/abstract-tangible-test.cpp
index 3bd1bdb28..05a49ed9a 100644
--- a/tests/gui/abstract-tangible-test.cpp
+++ b/tests/gui/abstract-tangible-test.cpp
@@ -46,6 +46,7 @@
 
 
 #include "lib/test/run.hpp"
+#include "lib/test/test-helper.hpp"
 //#include "gui/model/session-facade.hpp"
 //#include "gui/model/diagnostics.hpp"
 //#include "lib/util.hpp"
@@ -62,6 +63,8 @@
 //using std::cout;
 //using std::endl;
 
+using lib::error::LUMIERA_ERROR_ASSERTION;
+
 
 namespace gui  {
 namespace model{
@@ -110,9 +113,76 @@ namespace test {
       void
       verify_mockManipulation ()
         {
-          UNIMPLEMENTED ("setup and usage of an UI-Element mock");
+          MockElm mock("dummy");
+          mock.verify("ctor");
+          mock.verifyEvent("ctor");
+          mock.verify("ctor").arg("dummy");
+          
+          CHECK ("dummy" == mock.getID().getSym());
+          CHECK ("ID<gui::model::test::MockElm>-dummy" = string(mock.getID()));
+          
+          VERIFY_ERROR (ASSERTION, mock.verifyCall("reset"));
+          
+          mock.reset();
+          mock.verify("reset");
+          mock.verifyCall("reset");
+          mock.verifyEvent("reset");
+          mock.verify("reset").after("ctor");
+          mock.verify("ctor").before("reset");
+          VERIFY_ERROR (ASSERTION, mock.verify("reset").before("ctor"));
+          VERIFY_ERROR (ASSERTION, mock.verify("ctor").after("reset"));
+          
+          mock.verify("reset").before("reset");
+          mock.verify("reset").beforeEvent("reset");
+          mock.verifyCall("reset").before("reset");
+          mock.verifyCall("reset").beforeEvent("reset");
+          VERIFY_ERROR (ASSERTION, mock.verifyCall("reset").afterCall("reset"));
+          VERIFY_ERROR (ASSERTION, mock.verifyCall("reset").afterEvent("reset"));
+          VERIFY_ERROR (ASSERTION, mock.verifyEvent("reset").afterEvent("reset"));
+          
+          CHECK (!mock.isTouched());
+          CHECK (!mock.isExpanded());
+          
+          mock.noteMsg("dolorem ipsum quia dolor sit amet consectetur adipisci velit.");
+          mock.verifyNote("Msg");
+          mock.verifyCall("noteMsg");
+          mock.verifyCall("noteMsg").arg("lorem ipsum");
+          mock.verifyCall("noteMsg").argMatch("dolor.+dolor\\s+");
+          mock.verifyMatch("Rec\\(note.+kind = Msg.+msg = dolorem ipsum");
+          
+          EventLog log = mock.getLog();
+          log.verify("ctor")
+             .before("reset")
+             .before("lorem ipsum");
+          
+          MockElm foo("foo"), bar;
+          foo.verify("ctor").arg("foo");
+          bar.verify("ctor").arg();
+          
+          bar.ensureNot("foo");
+          log.ensureNot("foo");
+          mock.ensureNot("foo");
+          VERIFY_ERROR (ASSERTION, foo.ensureNot("foo"));
+          
+          log.join(bar).join(foo);
+          log.verifyEvent("logJoin").arg(bar.getID())
+             .beforeEvent("logJoin").arg("foo");
+          
+          mock.verifyEvent("logJoin").arg(bar.getID())
+              .beforeEvent("logJoin").arg("foo");
+          mock.verify("ctor").arg("foo");
+          log.verify("ctor").arg("foo");
+          log.verify("ctor").arg("dummy")
+             .before("ctor").arg(bar.getID())
+             .before("ctor").arg("foo");
+          
+          mock.kill();
+          foo.noteMsg("dummy killed");
+          log.verifyEvent("dtor").on("dummy")
+             .beforeCall("noteMsg").on("foo");
         }
       
+      
       void
       invokeCommand ()
         {
@@ -124,6 +194,8 @@ namespace test {
       markState ()
         {
           UNIMPLEMENTED ("mark interface state");
+          
+          TODO ("be sure also to cover signal diagnostics here");
         }
       
       
diff --git a/wiki/renderengine.html b/wiki/renderengine.html
index 027adeda4..2ff230278 100644
--- a/wiki/renderengine.html
+++ b/wiki/renderengine.html
@@ -8314,7 +8314,7 @@ The UI-Bus is a ''Mediator'' -- impersonating the role of the //Model// and the
 
 The ~MVC-Pattern as such is fine, and probably the best we know for construction of user interfaces. But it doesn't scale well towards the integration into a larger and more structured system. There is a tension between the Controller in the UI and other parts of an application, which as well need to be //in control.// And, even more important, there is a tension between the demands of UI elements for support by a model, and the demands to be placed on a core domain model of a large scale application. This tension is resolved by enacting these roles while transforming the requests and demands into //Messages.//</pre>
 </div>
-<div title="UI-Element" creator="Ichthyostega" modifier="Ichthyostega" created="201511210307" modified="201511261841" tags="GuiPattern design draft decision" changecount="12">
+<div title="UI-Element" creator="Ichthyostega" modifier="Ichthyostega" created="201511210307" modified="201511270107" tags="GuiPattern design draft decision" changecount="15">
 <pre>While our UI widgets are implemented the standard way as proposed by GTKmm, some key elements -- which are especially relevant for the anatomy and mechanics of the interface -- are made to conform to a common interface and behaviour protocol. {{red{WIP 11/15 work out what this protocol is all about}}}. #975
 As a starting point, we know
 * there is a backbone structure known as the UI-Bus
@@ -8352,9 +8352,9 @@ And finally, there are the //essential updates// -- any changes in the model //f
 :receive a GenNode representing the //feedback// or replayed //state mark//
 ;signals
 :the individual element exposes some generic signal slots
-:* sigMut prompts the element to draw a diff to alter its configuration
-:* sigExpand promts the element to transition into expanded / unfolded state. If this state is sticky, the element should answer with a ''mark''
-:* sigShow prompts the element to bring the indicated child into sight
+:* slotExpand prompts the element to transition into expanded / unfolded state. If this state is sticky, the element should answer with a ''mark''
+:* slotReveal prompts the element to bring the indicated child into sight
+:these slots are defined to be {{{sigc::trackable}}} for automated disconnection (&amp;rarr; see [[#940|http://issues.lumiera.org/ticket/940#comment:3]] for an explanation)
 ;diff
 :ask to retrieve a diff, which
 :* either is an incremental status update