diff -r 711de6b11ff1 -r 3c29351e939e AbstractTime.st
--- a/AbstractTime.st	Thu May 10 21:26:56 2018 +0200
+++ b/AbstractTime.st	Thu May 10 23:54:49 2018 +0200
@@ -852,7 +852,9 @@
     "return a new instance of myself, numberOfMilliSeconds afterwards."
 
     ^ self speciesNew 
-        setMilliseconds:(self getMilliseconds + numberOfMilliSeconds)
+        setMilliseconds:(self getMilliseconds + (numberOfMilliSeconds // 1))
+        additionalPicoseconds:(self additionalPicoseconds 
+                                + ((numberOfMilliSeconds \\ 1)*1000*1000*1000) rounded)
 
     "
      |t|
@@ -896,8 +898,7 @@
 addSeconds:numberOfSeconds
     "return a new instance of myself, numberOfSeconds afterwards."
 
-    ^ self speciesNew 
-        setMilliseconds:(self getMilliseconds + (numberOfSeconds * 1000))
+    ^ self addMilliseconds:(numberOfSeconds * 1000) 
 
     "
      |t|
@@ -1011,8 +1012,7 @@
 subtractMilliseconds:numberOfMilliSeconds
     "return a new instance of myself, numberOfMilliSeconds before."
 
-    ^ self speciesNew 
-        setMilliseconds:(self getMilliseconds - numberOfMilliSeconds)
+    ^ self addMilliseconds:numberOfMilliSeconds negated 
 
     "
      |t|
@@ -1056,8 +1056,7 @@
 subtractSeconds:numberOfSeconds
     "return a new instance of myself, numberOfSeconds before."
 
-    ^ self speciesNew 
-        setMilliseconds:(self getMilliseconds - (numberOfSeconds * 1000))
+    ^ self addMilliseconds:(numberOfSeconds * -1000) 
 
     "
      |t|
@@ -1105,20 +1104,143 @@
 
 !AbstractTime methodsFor:'comparing'!
 
-< aTime
+< aTimeOrTimeDurationOrNumberOfSeconds
     "return true if the receiver is before the argument"
 
-    ^ self getMilliseconds < aTime getMilliseconds
+    |myMilliseconds otherMilliseconds myPicos otherPicos|
+
+    myMilliseconds := self getMilliseconds.
+    myPicos := self additionalPicoseconds.
+
+    aTimeOrTimeDurationOrNumberOfSeconds isNumber ifTrue:[
+        "backward compatibility for old code, which expects (time1 - time2) to return seconds"    
+        otherMilliseconds := (aTimeOrTimeDurationOrNumberOfSeconds * 1000) asInteger.   "integer seconds"
+        otherPicos := 0.
+    ] ifFalse:[
+        otherMilliseconds := aTimeOrTimeDurationOrNumberOfSeconds getMilliseconds.
+        otherPicos := aTimeOrTimeDurationOrNumberOfSeconds additionalPicoseconds.
+    ].
+    ^ (myMilliseconds < otherMilliseconds)
+    or:[ myMilliseconds = otherMilliseconds and:[myPicos < otherPicos ]].
+
+    "
+        (Timestamp now + 10) - Timestamp now  < 10
+        (Timestamp now + 10) - Timestamp now  < 11
+    "
+!
 
-    "Modified: 3.7.1996 / 13:10:17 / cg"
+<= aTimeOrTimeDurationOrNumberOfSeconds
+    "return true if the receiver is before or the same time as the argument"
+
+    |myMilliseconds otherMilliseconds myPicos otherPicos|
+
+    myMilliseconds := self getMilliseconds.
+    myPicos := self additionalPicoseconds.
+
+    aTimeOrTimeDurationOrNumberOfSeconds isNumber ifTrue:[
+        "backward compatibility for old code, which expects (time1 - time2) to return seconds"    
+        otherMilliseconds := (aTimeOrTimeDurationOrNumberOfSeconds * 1000) asInteger.   "integer seconds"
+        otherPicos := 0.
+    ] ifFalse:[
+        otherMilliseconds := aTimeOrTimeDurationOrNumberOfSeconds getMilliseconds.
+        otherPicos := aTimeOrTimeDurationOrNumberOfSeconds additionalPicoseconds.
+    ].
+    ^ (myMilliseconds < otherMilliseconds)
+    or:[ myMilliseconds = otherMilliseconds and:[myPicos <= otherPicos ]].
+
+    "
+        (Timestamp now + 10) - Timestamp now  <= 10
+        (Timestamp now + 10) - Timestamp now  <= 11
+        (Timestamp now + 10) - Timestamp now  <= 9
+    "
 !
 
-> aTime
+= aTimeOrTimeDurationOrNumberOfSeconds
+    "return true if the receiver is before or the same time as the argument"
+
+    |myMilliseconds otherMilliseconds myPicos otherPicos|
+
+    myMilliseconds := self getMilliseconds.
+    myPicos := self additionalPicoseconds.
+
+    aTimeOrTimeDurationOrNumberOfSeconds isNumber ifTrue:[
+        "backward compatibility for old code, which expects (time1 - time2) to return seconds"    
+        otherMilliseconds := (aTimeOrTimeDurationOrNumberOfSeconds * 1000) asInteger.   "integer seconds"
+        otherPicos := 0.
+    ] ifFalse:[
+        otherMilliseconds := aTimeOrTimeDurationOrNumberOfSeconds getMilliseconds.
+        otherPicos := aTimeOrTimeDurationOrNumberOfSeconds additionalPicoseconds.
+    ].
+    ^ (myMilliseconds = otherMilliseconds) and:[myPicos = otherPicos ].
+
+    "
+        (Timestamp now + 10) - Timestamp now  = 10
+        (Timestamp now + 10) - Timestamp now  = 9
+
+        (Time now + 10 seconds) - Time now  = 10
+        (Time now + 10) - Time now          = 10
+
+        (Time now + 10 seconds) > Time now 
+        (Time now + 10)         > Time now      
+
+        (Time now + 10 milliSeconds) > Time now 
+        (Time now + 0 milliseconds)  > Time now      
+    "
+!
+
+> aTimeOrTimeDurationOrNumberOfSeconds
     "return true if the receiver is after the argument"
 
-    ^ self getMilliseconds > aTime getMilliseconds
+    |myMilliseconds otherMilliseconds myPicos otherPicos|
+
+    myMilliseconds := self getMilliseconds.
+    myPicos := self additionalPicoseconds.
+
+    aTimeOrTimeDurationOrNumberOfSeconds isNumber ifTrue:[
+        "backward compatibility for old code, which expects (time1 - time2) to return seconds"    
+        otherMilliseconds := (aTimeOrTimeDurationOrNumberOfSeconds * 1000) asInteger.   "integer seconds"
+        otherPicos := 0.
+    ] ifFalse:[
+        otherMilliseconds := aTimeOrTimeDurationOrNumberOfSeconds getMilliseconds.
+        otherPicos := aTimeOrTimeDurationOrNumberOfSeconds additionalPicoseconds.
+    ].
+    ^ (myMilliseconds > otherMilliseconds)
+    or:[ myMilliseconds = otherMilliseconds and:[myPicos > otherPicos ]].
+
+    "
+        (Timestamp now + 10) - Timestamp now  > 10
+        (Timestamp now + 10) - Timestamp now  > 9
+    "
+!
+
+>= aTimeOrTimeDurationOrNumberOfSeconds
+    "return true if the receiver is after the argument or the same"
 
-    "Modified: 1.7.1996 / 15:24:38 / cg"
+    |myMilliseconds otherMilliseconds myPicos otherPicos|
+
+    myMilliseconds := self getMilliseconds.
+    myPicos := self additionalPicoseconds.
+
+    aTimeOrTimeDurationOrNumberOfSeconds isNumber ifTrue:[
+        "backward compatibility for old code, which expects (time1 - time2) to return seconds"    
+        otherMilliseconds := (aTimeOrTimeDurationOrNumberOfSeconds * 1000) asInteger.   "integer seconds"
+        otherPicos := 0.
+    ] ifFalse:[
+        otherMilliseconds := aTimeOrTimeDurationOrNumberOfSeconds getMilliseconds.
+        otherPicos := aTimeOrTimeDurationOrNumberOfSeconds additionalPicoseconds.
+    ].
+    ^ (myMilliseconds > otherMilliseconds)
+    or:[ myMilliseconds = otherMilliseconds and:[myPicos >= otherPicos ]].
+
+    "
+        (Timestamp now + 10) - Timestamp now  >= 11
+        (Timestamp now + 10) - Timestamp now  >= 10
+        (Timestamp now + 10) - Timestamp now  >= 9
+    "
+!
+
+hash
+    ^ self getMilliseconds
 ! !
 
 !AbstractTime methodsFor:'converting'!