diff --git a/CMakeLists.txt b/CMakeLists.txt
index eb1c693..5e6ff61 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -11,7 +11,7 @@ file(GLOB_RECURSE  project_cxx ./src/*.cxx)
 file(GLOB_RECURSE  project_cc ./src/*.cc)
 
 if(UNIX)
-set(USE_SHIMLIB OFF)
+set(USE_SHIMLIB ON)
 else()
 set(USE_SHIMLIB OFF)
 endif()
diff --git a/src/ScanFormWidget.cpp b/src/ScanFormWidget.cpp
index e5e4824..583c189 100644
--- a/src/ScanFormWidget.cpp
+++ b/src/ScanFormWidget.cpp
@@ -206,7 +206,7 @@ ScanFormWidget::ScanFormWidget(QWidget* parent) : TabFormWidget(parent) {
 		painter.drawLine(800 - borderSpacing, borderSpacing + 1, 800 - borderSpacing, 800 - borderSpacing - 1);
 		pen.setColor(QColor(255, 255, 0));
 		painter.setPen(pen);
-		//        painter.drawText(335,40,"Previewing");
+		painter.drawText(335,40,QString("Previewing, current frame:%1").arg(++currentFrame));
 		painter.drawText(borderSpacing + 13, 400 + 13, "L");
 		painter.drawText(800 - borderSpacing - 30, 400 + 13, "R");
 		painter.drawText(400 - 13, borderSpacing + 30, "H");
diff --git a/src/ScanFormWidget.h b/src/ScanFormWidget.h
index d76526e..9984930 100644
--- a/src/ScanFormWidget.h
+++ b/src/ScanFormWidget.h
@@ -19,6 +19,7 @@ private:
     bool unset = true;
     bool previewing= false;
     std::function<void(bool)> previewfunc = nullptr;
+    int currentFrame = 0;
 private slots:
     void protocolChanged(int type);
 
diff --git a/src/json/cmdhelper.cpp b/src/json/cmdhelper.cpp
index aba41a5..69b1b6c 100644
--- a/src/json/cmdhelper.cpp
+++ b/src/json/cmdhelper.cpp
@@ -62,6 +62,7 @@ bool cmdHelper::getDiskUsed(double& used)
 	{
 		QString qstr = QString::fromStdString(str);
 		QStringList strList = qstr.split('\n');
+		if (strList.length()<3) return false;
 		strList[1].replace(QRegExp("[\\s]+"), " ");
 		QStringList strList2 = strList[1].split(" ");
 		int pos = strList2[2].lastIndexOf(QChar('G'));