diff --git a/gui/basewindow.cc b/gui/basewindow.cc
index c7e637f6..96799e85 100644
--- a/gui/basewindow.cc
+++ b/gui/basewindow.cc
@@ -80,10 +80,10 @@ BaseMainWindow::BaseMainWindow(std::unique_ptr<Context> context, QWidget *parent
     centralTabWidget->tabBar()->tabButton(0, QTabBar::RightSide)->resize(0, 0);
 
     connect(this, SIGNAL(contextChanged(Context *)), fpgaView, SLOT(newContext(Context *)));
-    connect(designview, SIGNAL(selected(std::vector<DecalXY>)), fpgaView,
-            SLOT(onSelectedArchItem(std::vector<DecalXY>)));
-    connect(fpgaView, SIGNAL(clickedBel(BelId)), designview, SLOT(onClickedBel(BelId)));
-    connect(fpgaView, SIGNAL(clickedWire(WireId)), designview, SLOT(onClickedWire(WireId)));
+    connect(designview, SIGNAL(selected(std::vector<DecalXY>, bool)), fpgaView,
+            SLOT(onSelectedArchItem(std::vector<DecalXY>, bool)));
+    connect(fpgaView, SIGNAL(clickedBel(BelId, bool)), designview, SLOT(onClickedBel(BelId, bool)));
+    connect(fpgaView, SIGNAL(clickedWire(WireId, bool)), designview, SLOT(onClickedWire(WireId, bool)));
 
     connect(designview, SIGNAL(highlight(std::vector<DecalXY>, int)), fpgaView,
             SLOT(onHighlightGroupChanged(std::vector<DecalXY>, int)));
diff --git a/gui/designwidget.cc b/gui/designwidget.cc
index 34f7a656..674c74c7 100644
--- a/gui/designwidget.cc
+++ b/gui/designwidget.cc
@@ -507,18 +507,18 @@ QtProperty *DesignWidget::addSubGroup(QtProperty *topItem, const QString &name)
     return item;
 }
 
-void DesignWidget::onClickedBel(BelId bel)
+void DesignWidget::onClickedBel(BelId bel, bool keep)
 {
     QTreeWidgetItem *item = nameToItem[getElementIndex(ElementType::BEL)].value(ctx->getBelName(bel).c_str(ctx));
     treeWidget->setCurrentItem(item);
-    Q_EMIT selected(getDecals(ElementType::BEL, ctx->getBelName(bel)));
+    Q_EMIT selected(getDecals(ElementType::BEL, ctx->getBelName(bel)), keep);
 }
 
-void DesignWidget::onClickedWire(WireId wire)
+void DesignWidget::onClickedWire(WireId wire, bool keep)
 {
     QTreeWidgetItem *item = nameToItem[getElementIndex(ElementType::WIRE)].value(ctx->getWireName(wire).c_str(ctx));
     treeWidget->setCurrentItem(item);
-    Q_EMIT selected(getDecals(ElementType::WIRE, ctx->getWireName(wire)));
+    Q_EMIT selected(getDecals(ElementType::WIRE, ctx->getWireName(wire)), keep);
 }
 
 void DesignWidget::onItemSelectionChanged()
@@ -534,7 +534,7 @@ void DesignWidget::onItemSelectionChanged()
             std::vector<DecalXY> d = getDecals(type, value);
             std::move(d.begin(), d.end(), std::back_inserter(decals));
         }
-        Q_EMIT selected(decals);
+        Q_EMIT selected(decals, false);
         return;
     }
 
@@ -555,7 +555,7 @@ void DesignWidget::onItemSelectionChanged()
     clearProperties();
 
     IdString c = static_cast<IdStringTreeItem *>(clickItem)->getData();
-    Q_EMIT selected(getDecals(type, c));
+    Q_EMIT selected(getDecals(type, c), false);
 
     if (type == ElementType::BEL) {
         BelId bel = ctx->getBelByName(c);
@@ -847,7 +847,7 @@ void DesignWidget::prepareMenuProperty(const QPoint &pos)
             std::vector<DecalXY> d = getDecals(type, value);
             std::move(d.begin(), d.end(), std::back_inserter(decals));
         }
-        Q_EMIT selected(decals);
+        Q_EMIT selected(decals, false);
     });
     menu.addAction(selectAction);
 
diff --git a/gui/designwidget.h b/gui/designwidget.h
index fec0d069..a11ed062 100644
--- a/gui/designwidget.h
+++ b/gui/designwidget.h
@@ -64,7 +64,7 @@ class DesignWidget : public QWidget
     void updateHighlightGroup(QList<QTreeWidgetItem *> item, int group);
   Q_SIGNALS:
     void info(std::string text);
-    void selected(std::vector<DecalXY> decal);
+    void selected(std::vector<DecalXY> decal, bool keep);
     void highlight(std::vector<DecalXY> decal, int group);
 
   private Q_SLOTS:
@@ -75,8 +75,8 @@ class DesignWidget : public QWidget
   public Q_SLOTS:
     void newContext(Context *ctx);
     void updateTree();
-    void onClickedBel(BelId bel);
-    void onClickedWire(WireId wire);
+    void onClickedBel(BelId bel, bool keep);
+    void onClickedWire(WireId wire, bool keep);
 
   private:
     Context *ctx;
diff --git a/gui/fpgaviewwidget.cc b/gui/fpgaviewwidget.cc
index 873800c5..5d7cb8ed 100644
--- a/gui/fpgaviewwidget.cc
+++ b/gui/fpgaviewwidget.cc
@@ -83,7 +83,7 @@ FPGAViewWidget::~FPGAViewWidget() {}
 void FPGAViewWidget::newContext(Context *ctx)
 {
     ctx_ = ctx;
-    onSelectedArchItem(std::vector<DecalXY>());
+    onSelectedArchItem(std::vector<DecalXY>(), false);
     for (int i = 0; i < 8; i++)
         onHighlightGroupChanged(std::vector<DecalXY>(), i);
     {
@@ -508,11 +508,15 @@ void FPGAViewWidget::renderLines(void)
     }
 }
 
-void FPGAViewWidget::onSelectedArchItem(std::vector<DecalXY> decals)
+void FPGAViewWidget::onSelectedArchItem(std::vector<DecalXY> decals, bool keep)
 {
     {
         QMutexLocker locker(&rendererArgsLock_);
-        rendererArgs_->selectedDecals = decals;
+        if (keep) {
+            std::copy(decals.begin(), decals.end(), std::back_inserter(rendererArgs_->selectedDecals));
+        } else {
+            rendererArgs_->selectedDecals = decals;
+        }
         rendererArgs_->changed = true;
     }
     pokeRenderer();
@@ -576,6 +580,8 @@ void FPGAViewWidget::mousePressEvent(QMouseEvent *event)
         lastDragPos_ = event->pos();
     }
     if (event->buttons() & Qt::LeftButton) {
+        bool ctrl = QApplication::keyboardModifiers().testFlag(Qt::ControlModifier);
+
         auto world = mouseToWorldCoordinates(event->x(), event->y());
         auto closestOr = pickElement(world.x(), world.y());
         if (!closestOr)
@@ -583,9 +589,9 @@ void FPGAViewWidget::mousePressEvent(QMouseEvent *event)
 
         auto closest = closestOr.value();
         if (closest.type == ElementType::BEL) {
-            clickedBel(closest.element.bel);
+            clickedBel(closest.element.bel, ctrl);
         } else if (closest.type == ElementType::WIRE) {
-            clickedWire(closest.element.wire);
+            clickedWire(closest.element.wire, ctrl);
         }
     }
 }
diff --git a/gui/fpgaviewwidget.h b/gui/fpgaviewwidget.h
index 732f4e3e..335ee51b 100644
--- a/gui/fpgaviewwidget.h
+++ b/gui/fpgaviewwidget.h
@@ -110,7 +110,7 @@ class FPGAViewWidget : public QOpenGLWidget, protected QOpenGLFunctions
 
   public Q_SLOTS:
     void newContext(Context *ctx);
-    void onSelectedArchItem(std::vector<DecalXY> decals);
+    void onSelectedArchItem(std::vector<DecalXY> decals, bool keep);
     void onHighlightGroupChanged(std::vector<DecalXY> decals, int group);
     void pokeRenderer(void);
     void zoomIn();
@@ -119,8 +119,8 @@ class FPGAViewWidget : public QOpenGLWidget, protected QOpenGLFunctions
     void zoomOutbound();
 
   Q_SIGNALS:
-    void clickedBel(BelId bel);
-    void clickedWire(WireId wire);
+    void clickedBel(BelId bel, bool add);
+    void clickedWire(WireId wire, bool add);
 
   private:
     const float zoomNear_ = 0.1f;  // do not zoom closer than this