make sure that on cursor metrical sig crossing we start at 0 ticks internally

engine/track.py

@@ -557,7 +557,7 @@ class Track(object):
 
     def right(self):
         if self.currentBlock().right(): #side effect: actual moving
-            self.parseRight()
+            self.parseRight() #we parse the previous item
             return 1
         elif self.state.blockindex+1 < len(self.blocks): #block counts from 0, len from 1. If block+1 is smaller than the amount of blocks this means this is not the final block.
             #block end. This is already the previous state. right now we are in the next block already.
@@ -600,7 +600,10 @@ class Track(object):
                 break
 
     def measureStart(self):
-        if self.state.ticksSinceLastMeasureStartLive < 0: #upbeats are lower than 0
+        if self.state.ticksSinceLastMeasureStartLive == 0:
+            #Already at the start
+            return
+        elif self.state.ticksSinceLastMeasureStartLive < 0: #upbeats are lower than 0
             while not self.state.ticksSinceLastMeasureStartLive == 0:
                 self.right()
         else:
@@ -614,6 +617,8 @@ class Track(object):
             else:
                 self.head()
 
+        assert self.state.ticksSinceLastMeasureStartLive == 0, self.state.ticksSinceLastMeasureStartLive
+
     def startOfBlock(self):
         currentBlock = self.currentBlock() #we stay in this block so this doesn't need to change.
         while not currentBlock.localCursorIndex == 0:
@@ -792,6 +797,7 @@ class Track(object):
             self.state.keySignatures.append(item)
         elif isinstance(item, MetricalInstruction):
             self.state.metricalInstructions.append(item)
+            self.state.ticksSinceLastMeasureStartLive = 0 #by definition.
         elif isinstance(item, DynamicSignature):
             self.state.dynamicSignatures.append(item)
             self.state.dynamicRamp = None #reset