fix picker which crashed on resolution change, timelapse frame only when draw a stroke

engine/canvas_modes.cpp

@@ -99,6 +99,7 @@ void CanvasModePen::on_MouseEvent(MouseEvent* me, glm::vec2& loc)
                 glm::vec4 pix = canvas->pick_get(loc);
                 canvas->m_current_brush.m_tip_color = pix;
                 App::I.color->set_color(pix);
+                canvas->pick_end();
             }
             m_dragging = false;
             m_picking = false;