Allow left button to scroll ScrollWidget, so that the rack and other scroll containers can be scrolled with a touch screen.

src/app/ModuleWidget.cpp

@@ -355,7 +355,12 @@ void ModuleWidget::drawShadow(const DrawArgs& args) {
 }
 
 void ModuleWidget::onButton(const event::Button& e) {
-	OpaqueWidget::onButton(e);
+	// Don't consume left button if `lockModules` is enabled.
+	if (settings::lockModules)
+		Widget::onButton(e);
+	else
+		OpaqueWidget::onButton(e);
+
 	if (e.isConsumed())
 		return;
 

src/app/RackScrollWidget.cpp

@@ -75,7 +75,6 @@ void RackScrollWidget::step() {
 	oldOffset = offset;
 }
 
-
 void RackScrollWidget::draw(const DrawArgs& args) {
 	// Hide scrollbars if full screen
 	bool fullscreen = APP->window->isFullScreen();

src/engine/Engine.cpp

@@ -528,16 +528,19 @@ long Engine::getFrame() {
 
 
 long Engine::getStepFrame() {
+	// No lock, for performance
 	return internal->stepFrame;
 }
 
 
 long Engine::getStepTime() {
+	// No lock, for performance
 	return internal->stepTime;
 }
 
 
 int Engine::getStepFrames() {
+	// No lock, for performance
 	return internal->stepFrames;
 }
 

src/ui/ScrollWidget.cpp

@@ -64,7 +64,7 @@ void ScrollWidget::step() {
 }
 
 void ScrollWidget::onButton(const event::Button& e) {
-	Widget::onButton(e);
+	OpaqueWidget::onButton(e);
 	if (e.isConsumed())
 		return;
 
@@ -78,7 +78,7 @@ void ScrollWidget::onButton(const event::Button& e) {
 }
 
 void ScrollWidget::onDragStart(const event::DragStart& e) {
-	if (e.button == GLFW_MOUSE_BUTTON_MIDDLE) {
+	if (e.button == GLFW_MOUSE_BUTTON_LEFT || e.button == GLFW_MOUSE_BUTTON_MIDDLE) {
 		e.consume(this);
 	}
 }