Rework the step functions.

Windows/Debugger/Debugger_Disasm.cpp

@@ -208,11 +208,19 @@ void CDisasm::step(CPUStepType stepType)
 	ptr->setDontRedraw(true);
 	lastTicks_ = CoreTiming::GetTicks();
 
-	u32 stepSize = ptr->getInstructionSizeAt(cpu->GetPC());
-	u32 newAddress = Core_PerformStep(cpu, stepType, stepSize);
+	u32 oldAddress = cpu->GetPC();
+	u32 stepSize = ptr->getInstructionSizeAt(oldAddress);
+	Core_PerformStep(cpu, stepType, stepSize);
 
 	Sleep(1);
-	ptr->scrollStepping(newAddress);
+	// At this point, the step should be done, and the new address is just PC.
+	// Ideally, this part should be done as a reaction to an update message and not directly here.
+	// That way we could get rid of the sleep.
+	u32 newAddress = cpu->GetPC();
+	if (newAddress > oldAddress && newAddress < oldAddress + 12) {
+		// Heuristic for when to scroll at the edge rather than jump the window.
+		ptr->scrollStepping(newAddress);
+	}
 	ptr->gotoAddr(newAddress);
 	UpdateDialog();
 }