Simulation hangs if datarate-channel delay value is too close to simtime-resolution

[mody]

Take for example https://github.com/inet-framework/inet/tree/master/examples/inet/udpburst

Apply these two changes.

diff --git a/examples/inet/udpburst/UDPBurst.ned b/examples/inet/udpburst/UDPBurst.ned
index 69ff10a969..f2f7f43f3b 100644
--- a/examples/inet/udpburst/UDPBurst.ned
+++ b/examples/inet/udpburst/UDPBurst.ned
@@ -14,7 +14,7 @@ network UDPBurst
         channel C extends DatarateChannel
         {
             datarate = 1Mbps;
-            delay = 0.1us;
+            delay = 10ns;
         }
     submodules:
         host[numhosts]: StandardHost {

diff --git a/examples/inet/udpburst/omnetpp.ini b/examples/inet/udpburst/omnetpp.ini
index 1929919758..79fe314812 100644
--- a/examples/inet/udpburst/omnetpp.ini
+++ b/examples/inet/udpburst/omnetpp.ini
@@ -1,6 +1,7 @@
 [General]
 network = UDPBurst
 total-stack = 7MiB
+simtime-resolution = ns
 
 **.numhosts = 5
 # udp app configuration

Running the simulation hangs as soon as there is a packet to draw. Right-click twice anywhere for the simulation to move a bit and hand again.

Increase the delay above ~70ns and packets start to move. YMMV.

Change the simtime-resolution to ps and suddenly all work.

If the delay parameter of the dataratechannel is too close to the simtime-resolution time resolution, the drawing starts to behave erratic and even hangs the whole simulation.

This may be an issue with OMNeT++ and their handling of simtime-resolution.

EDIT:

To be presice, the hang happens when the simulation is run using GUI and on the normal/presentation speed. Running without GUI or running it faster with GUI doesn't hang.