I'm playing with latest trunk on linux 64bit, and got this crash after activating move vertex tool and click on the canvas:
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fae7e3b0710 (LWP 15029)]
0x00007fae7de45157 in QString::operator= () from /usr/lib/libQtCore.so.4
(gdb) bt
#0 0x00007fae7de45157 in QString::operator= () from /usr/lib/libQtCore.so.4
#1 0x00007fae7c3bc571 in QgsCoordinateReferenceSystem::operator= () from /usr/local/lib/libqgis_core.so.1.4.0
#2 0x00007fae7c35405f in QgsCoordinateTransform::QgsCoordinateTransform () from /usr/local/lib/libqgis_core.so.1.4.0
#3 0x00007fae7c38be49 in QgsMapRenderer::mapToLayerCoordinates () from /usr/local/lib/libqgis_core.so.1.4.0
#4 0x00007fae7c3b3825 in QgsSnapper::snapPoint () from /usr/local/lib/libqgis_core.so.1.4.0
#5 0x00007fae7bfebb8d in QgsMapCanvasSnapper::snapToBackgroundLayers () from /usr/local/lib/libqgis_gui.so.1.4.0
#6 0x000000000058a68f in QgsMapToolMoveVertex::canvasMoveEvent ()
#7 0x00007fae7bfe4582 in QgsMapCanvas::mouseMoveEvent () from /usr/local/lib/libqgis_gui.so.1.4.0
#8 0x00007fae7d453512 in QWidget::event () from /usr/lib/libQtGui.so.4
#9 0x00007fae7d752a76 in QFrame::event () from /usr/lib/libQtGui.so.4
#10 0x00007fae7d7d7169 in QAbstractScrollArea::viewportEvent () from /usr/lib/libQtGui.so.4
#11 0x00007fae7d9436f1 in QGraphicsView::viewportEvent () from /usr/lib/libQtGui.so.4
#12 0x00007fae7d7d8308 in ?? () from /usr/lib/libQtGui.so.4
#13 0x00007fae7dee740e in QCoreApplicationPrivate::sendThroughObjectEventFilters () from /usr/lib/libQtCore.so.4
#14 0x00007fae7d405520 in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#15 0x00007fae7d40a329 in QApplication::notify () from /usr/lib/libQtGui.so.4
#16 0x00007fae7c34d3f4 in QgsApplication::notify () from /usr/local/lib/libqgis_core.so.1.4.0
#17 0x00007fae7dee7109 in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#18 0x00007fae7d407455 in QApplicationPrivate::sendMouseEvent () from /usr/lib/libQtGui.so.4
#19 0x00007fae7d469756 in ?? () from /usr/lib/libQtGui.so.4
#20 0x00007fae7d46866b in QApplication::x11ProcessEvent () from /usr/lib/libQtGui.so.4
#21 0x00007fae7d48e8f3 in ?? () from /usr/lib/libQtGui.so.4
#22 0x00007fae79a4c384 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#23 0x00007fae79a4f695 in ?? () from /usr/lib/libglib-2.0.so.0
#24 0x00007fae79a4fb7b in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#25 0x00007fae7df103af in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#26 0x00007fae7d48e72f in ?? () from /usr/lib/libQtGui.so.4
