2 files changed, 30 insertions, 0 deletions
diff --git a/src/MainWindow.h b/src/MainWindow.h
index f555906..2c43856 100644
--- a/src/MainWindow.h
+++ b/src/MainWindow.h
@@ -157,4 +157,19 @@ public slots:
 	void autoReloadSet(bool);
 };
 
+class GuiLocker
+{
+public:
+	GuiLocker() {
+		gui_locked++;
+	}
+	~GuiLocker() {
+		gui_locked--;
+	}
+	static bool isLocked() { return gui_locked > 0; }
+
+private:
+	static unsigned int gui_locked;
+};
+
 #endif
diff --git a/src/mainwin.cc b/src/mainwin.cc
index 16ad59d..7b69190 100644
--- a/src/mainwin.cc
+++ b/src/mainwin.cc
@@ -117,6 +117,9 @@ using CGAL::OGL::Nef3_Converter;
 #endif
 #endif // ENABLE_CGAL
 
+// Global application state
+unsigned int GuiLocker::gui_locked = 0;
+
 #define QUOTE(x__) # x__
 #define QUOTED(x__) QUOTE(x__)
 
@@ -592,6 +595,7 @@ void MainWindow::compile(bool procevents)
 	this->background_chain = NULL;
 
 	this->root_node = NULL;
+	this->tree.setRoot(NULL);
 	this->enableOpenCSG = false;
 
 	// Initialize special variables
@@ -1040,6 +1044,9 @@ bool MainWindow::checkModified()
 
 void MainWindow::actionReloadCompile()
 {
+	if (GuiLocker::isLocked()) return;
+	GuiLocker lock;
+
 	if (!checkModified()) return;
 
 	console->clear();
@@ -1065,6 +1072,9 @@ void MainWindow::actionReloadCompile()
 
 void MainWindow::actionCompile()
 {
+	if (GuiLocker::isLocked()) return;
+	GuiLocker lock;
+
 	setCurrentOutput();
 	console->clear();
 
@@ -1099,6 +1109,9 @@ void MainWindow::actionCompile()
 
 void MainWindow::actionRenderCGAL()
 {
+	if (GuiLocker::isLocked()) return;
+	GuiLocker lock;
+
 	setCurrentOutput();
 	console->clear();
 
@@ -1273,6 +1286,8 @@ void MainWindow::actionExportSTLorOFF(bool stl_mode)
 void MainWindow::actionExportSTLorOFF(bool)
 #endif
 {
+	if (GuiLocker::isLocked()) return;
+	GuiLocker lock;
 #ifdef ENABLE_CGAL
 	setCurrentOutput();