timeline/viewer: set minimum on rationalslider

app/widget/playbackcontrols/playbackcontrols.cpp

@@ -55,6 +55,7 @@ PlaybackControls::PlaybackControls(QWidget *parent) :
 
   cur_tc_lbl_ = new RationalSlider();
   cur_tc_lbl_->SetDisplayType(RationalSlider::kTime);
+  cur_tc_lbl_->SetMinimum(0);
   connect(cur_tc_lbl_, &RationalSlider::ValueChanged, this, &PlaybackControls::TimeChanged);
   lower_left_layout->addWidget(cur_tc_lbl_);
   lower_left_layout->addStretch();

app/widget/timelinewidget/timelinewidget.cpp

@@ -76,6 +76,7 @@ TimelineWidget::TimelineWidget(QWidget *parent) :
   timecode_label_->SetAlignment(Qt::AlignCenter);
   timecode_label_->SetDisplayType(RationalSlider::kTime);
   timecode_label_->setVisible(false);
+  timecode_label_->SetMinimum(0);
   connect(timecode_label_, &RationalSlider::ValueChanged, this, &TimelineWidget::SetTimeAndSignal);
   ruler_and_time_layout->addWidget(timecode_label_);