I can get anywhere between 1 & 3 clicks on sequenced effects within the grid before the program crashes and OS X produces a crash report, snippet below for the crashed thread. Rolled back to 4.1.6 and there are no problems with clicking effects.
Crashed Thread: 9
Exception Type: EXC_CRASH (SIGABRT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Application Specific Information:
abort() called
*** error for object 0x10dd94437: pointer being realloc'd was not allocated
Thread 9 Crashed:
0 libsystem_kernel.dylib 0x00007fff9d1ce286 __pthread_kill + 10
1 libsystem_c.dylib 0x00007fff95979b53 abort + 129
2 libsystem_malloc.dylib 0x00007fff92eb53cd realloc + 385
3 xLights.xLights 0x000000010dd9445b wxString::AsChar(wxMBConv const&) const + 107
4 xLights.xLights 0x000000010d8f58ac xLightsFrame::RenderEffectFromMap(Effect*, int, int, SettingsMap const&, PixelBufferClass&, bool&, bool, RenderEvent*) + 54044
5 xLights.xLights 0x000000010d91ac22 RenderJob::Process() + 4114
6 xLights.xLights 0x000000010d8a0d5f JobPoolWorker::Entry() + 47
7 xLights.xLights 0x000000010dde8f9f wxThread::CallEntry() + 15
8 xLights.xLights 0x000000010dde88b6 wxThreadInternal::PthreadStart(wxThread*) + 2662
9 libsystem_pthread.dylib 0x00007fff9a29b268 _pthread_body + 131
10 libsystem_pthread.dylib 0x00007fff9a29b1e5 _pthread_start + 176
11 libsystem_pthread.dylib 0x00007fff9a29941d thread_start + 13
Thread 10:
Thread 9 crashed with X86 Thread State (64-bit):
rax: 0x0000000000000000 rbx: 0x0000000000000006 rcx: 0x0000000116aabb78 rdx: 0x0000000000000000
rdi: 0x000000000001095f rsi: 0x0000000000000006 rbp: 0x0000000116aabba0 rsp: 0x0000000116aabb78
r8: 0x0000000000000001 r9: 0x0000000000000000 r10: 0x0000000008000000 r11: 0x0000000000000206
r12: 0x000000010dd94437 r13: 0x0000000000000005 r14: 0x0000000116ab2000 r15: 0x0000000000000001
rip: 0x00007fff9d1ce286 rfl: 0x0000000000000206 cr2: 0x00007fff7e98efd8
Logical CPU: 0
Error Code: 0x02000148
Trap Number: 133