diff --git a/common/lc_library.cpp b/common/lc_library.cpp
index 24619a25..a00aa371 100644
--- a/common/lc_library.cpp
+++ b/common/lc_library.cpp
@@ -315,9 +315,17 @@ void lcPiecesLibrary::ReadArchiveDescriptions(const QString& OfficialFileName, c
 	QFileInfo UnofficialInfo(UnofficialFileName);
 	
 	mArchiveCheckSum[0] = OfficialInfo.size();
+#if (QT_VERSION >= QT_VERSION_CHECK(4, 7, 0))
 	mArchiveCheckSum[1] = OfficialInfo.lastModified().toMSecsSinceEpoch();
+#else
+	mArchiveCheckSum[1] = OfficialInfo.lastModified().toTime_t();
+#endif
 	mArchiveCheckSum[2] = UnofficialInfo.size();
+#if (QT_VERSION >= QT_VERSION_CHECK(4, 7, 0))
 	mArchiveCheckSum[3] = UnofficialInfo.lastModified().toMSecsSinceEpoch();
+#else
+	mArchiveCheckSum[3] = UnofficialInfo.lastModified().toTime_t();
+#endif
 
 	QString IndexFileName = QFileInfo(QDir(mCachePath), QLatin1String("index")).absoluteFilePath();
 
diff --git a/common/lc_mainwindow.cpp b/common/lc_mainwindow.cpp
index dfd60c09..0d3f3c78 100644
--- a/common/lc_mainwindow.cpp
+++ b/common/lc_mainwindow.cpp
@@ -810,11 +810,15 @@ void lcMainWindow::Print(QPrinter* Printer)
 	if (Printer->collateCopies())
 	{
 		DocCopies = 1;
+#if (QT_VERSION >= QT_VERSION_CHECK(4, 7, 0))
 		PageCopies = Printer->supportsMultipleCopies() ? 1 : Printer->copyCount();
+#endif
 	}
 	else
 	{
+#if (QT_VERSION >= QT_VERSION_CHECK(4, 7, 0))
 		DocCopies = Printer->supportsMultipleCopies() ? 1 : Printer->copyCount();
+#endif
 		PageCopies = 1;
 	}
 
diff --git a/common/lc_shortcuts.cpp b/common/lc_shortcuts.cpp
index 194a9f90..5af11d99 100644
--- a/common/lc_shortcuts.cpp
+++ b/common/lc_shortcuts.cpp
@@ -133,8 +133,10 @@ void lcMouseShortcuts::Reset()
 	memset(mShortcuts, 0, sizeof(mShortcuts));
 	mShortcuts[LC_TOOL_ROTATE_VIEW].Modifiers = Qt::AltModifier;
 	mShortcuts[LC_TOOL_ROTATE_VIEW].Button = Qt::LeftButton;
+#if (QT_VERSION >= QT_VERSION_CHECK(4, 7, 0))
 	mShortcuts[LC_TOOL_PAN].Modifiers = Qt::AltModifier;
 	mShortcuts[LC_TOOL_PAN].Button = Qt::MiddleButton;
+#endif
 	mShortcuts[LC_TOOL_ZOOM].Modifiers = Qt::AltModifier;
 	mShortcuts[LC_TOOL_ZOOM].Button = Qt::RightButton;
 }
diff --git a/common/lc_timelinewidget.cpp b/common/lc_timelinewidget.cpp
index d9215c60..55f9aec4 100644
--- a/common/lc_timelinewidget.cpp
+++ b/common/lc_timelinewidget.cpp
@@ -178,8 +178,7 @@ void lcTimelineWidget::Update(bool Clear, bool UpdateItems)
 				int Size = rowHeight(indexFromItem(PieceItem));
 
 				QImage Image(Size, Size, QImage::Format_ARGB32);
-				Image.fill(QColor::fromRgbF(1.0, 1.0, 1.0, 0.0));
-
+				Image.fill(0);
 				float* Color = gColorList[ColorIndex].Value;
 				QPainter Painter(&Image);
 				Painter.setPen(Qt::NoPen);
diff --git a/common/project.cpp b/common/project.cpp
index a7fbca19..baf6ec8c 100644
--- a/common/project.cpp
+++ b/common/project.cpp
@@ -172,7 +172,9 @@ lcModel* Project::CreateNewModel(bool ShowModel)
 void Project::ShowModelListDialog()
 {
 	QList<QPair<QString, lcModel*>> Models;
+#if (QT_VERSION >= QT_VERSION_CHECK(4, 7, 0))
 	Models.reserve(mModels.GetSize());
+#endif
 
 	for (int ModelIdx = 0; ModelIdx < mModels.GetSize(); ModelIdx++)
 	{
diff --git a/common/view.cpp b/common/view.cpp
index b1912697..2059d982 100644
--- a/common/view.cpp
+++ b/common/view.cpp
@@ -2519,7 +2519,7 @@ void View::OnMiddleButtonDown()
 	}
 
 	gMainWindow->SetActiveView(this);
-
+#if (QT_VERSION >= QT_VERSION_CHECK(4, 7, 0))
 	lcTrackTool OverrideTool = GetOverrideTrackTool(Qt::MiddleButton);
 
 	if (OverrideTool != LC_TRACKTOOL_NONE)
@@ -2527,7 +2527,7 @@ void View::OnMiddleButtonDown()
 		mTrackTool = OverrideTool;
 		OnUpdateCursor();
 	}
-
+#endif
 	OnButtonDown(LC_TRACKBUTTON_MIDDLE);
 }
 
diff --git a/qt/lc_qarraydialog.cpp b/qt/lc_qarraydialog.cpp
index 43dabeb4..a84e6e09 100644
--- a/qt/lc_qarraydialog.cpp
+++ b/qt/lc_qarraydialog.cpp
@@ -8,24 +8,24 @@ lcQArrayDialog::lcQArrayDialog(QWidget* Parent)
 {
 	ui->setupUi(this);
 
-	ui->offset1x->setValidator(new QDoubleValidator());
-	ui->offset1y->setValidator(new QDoubleValidator());
-	ui->offset1z->setValidator(new QDoubleValidator());
-	ui->offset2x->setValidator(new QDoubleValidator());
-	ui->offset2y->setValidator(new QDoubleValidator());
-	ui->offset2z->setValidator(new QDoubleValidator());
-	ui->offset3x->setValidator(new QDoubleValidator());
-	ui->offset3y->setValidator(new QDoubleValidator());
-	ui->offset3z->setValidator(new QDoubleValidator());
-	ui->rotation1x->setValidator(new QDoubleValidator());
-	ui->rotation1y->setValidator(new QDoubleValidator());
-	ui->rotation1z->setValidator(new QDoubleValidator());
-	ui->rotation2x->setValidator(new QDoubleValidator());
-	ui->rotation2y->setValidator(new QDoubleValidator());
-	ui->rotation2z->setValidator(new QDoubleValidator());
-	ui->rotation3x->setValidator(new QDoubleValidator());
-	ui->rotation3y->setValidator(new QDoubleValidator());
-	ui->rotation3z->setValidator(new QDoubleValidator());
+	ui->offset1x->setValidator(new QDoubleValidator(ui->offset1x));
+	ui->offset1y->setValidator(new QDoubleValidator(ui->offset1y));
+	ui->offset1z->setValidator(new QDoubleValidator(ui->offset1z));
+	ui->offset2x->setValidator(new QDoubleValidator(ui->offset2x));
+	ui->offset2y->setValidator(new QDoubleValidator(ui->offset2y));
+	ui->offset2z->setValidator(new QDoubleValidator(ui->offset2z));
+	ui->offset3x->setValidator(new QDoubleValidator(ui->offset3x));
+	ui->offset3y->setValidator(new QDoubleValidator(ui->offset3y));
+	ui->offset3z->setValidator(new QDoubleValidator(ui->offset3z));
+	ui->rotation1x->setValidator(new QDoubleValidator(ui->rotation1x));
+	ui->rotation1y->setValidator(new QDoubleValidator(ui->rotation1y));
+	ui->rotation1z->setValidator(new QDoubleValidator(ui->rotation1z));
+	ui->rotation2x->setValidator(new QDoubleValidator(ui->rotation2x));
+	ui->rotation2y->setValidator(new QDoubleValidator(ui->rotation2y));
+	ui->rotation2z->setValidator(new QDoubleValidator(ui->rotation2z));
+	ui->rotation3x->setValidator(new QDoubleValidator(ui->rotation3x));
+	ui->rotation3y->setValidator(new QDoubleValidator(ui->rotation3y));
+	ui->rotation3z->setValidator(new QDoubleValidator(ui->rotation3z));
 
 	mCounts[0] = 10;
 	mCounts[1] = 1;
diff --git a/qt/lc_qhtmldialog.cpp b/qt/lc_qhtmldialog.cpp
index 7f524694..98410bdf 100644
--- a/qt/lc_qhtmldialog.cpp
+++ b/qt/lc_qhtmldialog.cpp
@@ -9,10 +9,10 @@ lcQHTMLDialog::lcQHTMLDialog(QWidget *parent, void *data) :
 {
     ui->setupUi(this);
 
-	ui->stepWidth->setValidator(new QIntValidator(0, 2048));
-	ui->stepHeight->setValidator(new QIntValidator(0, 2048));
-	ui->partImagesWidth->setValidator(new QIntValidator(0, 2048));
-	ui->partImagesHeight->setValidator(new QIntValidator(0, 2048));
+	ui->stepWidth->setValidator(new QIntValidator(0, 2048, ui->stepWidth));
+	ui->stepHeight->setValidator(new QIntValidator(0, 2048, ui->stepHeight));
+	ui->partImagesWidth->setValidator(new QIntValidator(0, 2048, ui->partImagesWidth));
+	ui->partImagesHeight->setValidator(new QIntValidator(0, 2048, ui->partImagesHeight));
 
 	options = (lcHTMLDialogOptions*)data;
 
diff --git a/qt/lc_qpreferencesdialog.cpp b/qt/lc_qpreferencesdialog.cpp
index 09e278af..2c87730c 100644
--- a/qt/lc_qpreferencesdialog.cpp
+++ b/qt/lc_qpreferencesdialog.cpp
@@ -15,7 +15,7 @@ lcQPreferencesDialog::lcQPreferencesDialog(QWidget *parent, void *data) :
 {
     ui->setupUi(this);
 
-	ui->lineWidth->setValidator(new QDoubleValidator());
+	ui->lineWidth->setValidator(new QDoubleValidator(ui->lineWidth));
 	connect(ui->gridStudColor, SIGNAL(clicked()), this, SLOT(colorClicked()));
 	connect(ui->gridLineColor, SIGNAL(clicked()), this, SLOT(colorClicked()));
 	connect(ui->categoriesTree, SIGNAL(itemSelectionChanged()), this, SLOT(updateParts()));
@@ -617,9 +617,11 @@ void lcQPreferencesDialog::UpdateMouseTreeItem(int ItemIndex)
 		Shortcut += tr("Left Button");
 		break;
 
+#if (QT_VERSION >= QT_VERSION_CHECK(4, 7, 0))
 	case Qt::MiddleButton:
 		Shortcut += tr("Middle Button");
 		break;
+#endif
 
 	case Qt::RightButton:
 		Shortcut += tr("Right Button");
@@ -656,9 +658,11 @@ void lcQPreferencesDialog::on_mouseAssign_clicked()
 			Button = Qt::LeftButton;
 			break;
 
+#if (QT_VERSION >= QT_VERSION_CHECK(4, 7, 0))
 		case 2:
 			Button = Qt::MiddleButton;
 			break;
+#endif
 
 		case 3:
 			Button = Qt::RightButton;
@@ -746,9 +750,11 @@ void lcQPreferencesDialog::MouseTreeItemChanged(QTreeWidgetItem* Current)
 		ui->mouseButton->setCurrentIndex(1);
 		break;
 
+#if (QT_VERSION >= QT_VERSION_CHECK(4, 7, 0))
 	case Qt::MiddleButton:
 		ui->mouseButton->setCurrentIndex(2);
 		break;
+#endif
 
 	case Qt::RightButton:
 		ui->mouseButton->setCurrentIndex(3);
diff --git a/qt/lc_qpropertiesdialog.cpp b/qt/lc_qpropertiesdialog.cpp
index deccbeb6..0dd0d47b 100644
--- a/qt/lc_qpropertiesdialog.cpp
+++ b/qt/lc_qpropertiesdialog.cpp
@@ -14,7 +14,7 @@ lcQPropertiesDialog::lcQPropertiesDialog(QWidget *parent, void *data) :
 {
 	ui->setupUi(this);
 
-	ui->fogDensityEdit->setValidator(new QDoubleValidator());
+	ui->fogDensityEdit->setValidator(new QDoubleValidator(ui->fogDensityEdit));
 
 	connect(ui->solidColorButton, SIGNAL(clicked()), this, SLOT(colorClicked()));
 	connect(ui->gradient1ColorButton, SIGNAL(clicked()), this, SLOT(colorClicked()));
diff --git a/qt/lc_qpropertiestree.cpp b/qt/lc_qpropertiestree.cpp
index e57e3e41..e3a9bad9 100644
--- a/qt/lc_qpropertiestree.cpp
+++ b/qt/lc_qpropertiestree.cpp
@@ -424,7 +424,7 @@ QWidget *lcQPropertiesTree::createEditor(QWidget *parent, QTreeWidgetItem *item)
 			QLineEdit *editor = new QLineEdit(parent);
 			float value = item->data(0, PropertyValueRole).toFloat();
 
-			editor->setValidator(new QDoubleValidator());
+			editor->setValidator(new QDoubleValidator(editor));
 			editor->setText(lcFormatValueLocalized(value));
 
 			connect(editor, SIGNAL(returnPressed()), this, SLOT(slotReturnPressed()));
diff --git a/qt/lc_qupdatedialog.cpp b/qt/lc_qupdatedialog.cpp
index 5e378dbd..f8c6efc2 100644
--- a/qt/lc_qupdatedialog.cpp
+++ b/qt/lc_qupdatedialog.cpp
@@ -19,7 +19,11 @@ void lcDoInitialUpdateCheck()
 	{
 		QDateTime NextCheckTime = CheckTime.addDays(updateFrequency == 1 ? 1 : 7);
 
+#if (QT_VERSION >= QT_VERSION_CHECK(4, 7, 0))
 		if (NextCheckTime > QDateTime::currentDateTimeUtc())
+#else
+		if (NextCheckTime > QDateTime::currentDateTime())
+#endif
 			return;
 	}
 
@@ -147,7 +151,11 @@ void lcQUpdateDialog::replyFinished(QNetworkReply *reply)
 		else
 			ui->status->setText(tr("Error parsing update information."));
 
+#if (QT_VERSION >= QT_VERSION_CHECK(4, 7, 0))
 		settings.setValue("Updates/LastCheck", QDateTime::currentDateTimeUtc());
+#else
+		settings.setValue("Updates/LastCheck", QDateTime::currentDateTime());
+#endif
 
 		updateReply = NULL;
 		reply->deleteLater();