fix(table): table scrolls before selected reaches top/bottom (charmbr…

…acelet#429)

* Fix bug in moving up in table

* fix

* Fix table viewport scroll down too early

table/table.go

@@ -347,7 +347,7 @@ func (m *Model) MoveUp(n int) {
  case m.start == 0:
  m.viewport.SetYOffset(clamp(m.viewport.YOffset, 0, m.cursor))
  case m.start < m.viewport.Height:
- m.viewport.SetYOffset(clamp(m.viewport.YOffset+n, 0, m.cursor))
+ m.viewport.YOffset = (clamp(clamp(m.viewport.YOffset+n, 0, m.cursor), 0, m.viewport.Height))
  case m.viewport.YOffset >= 1:
  m.viewport.YOffset = clamp(m.viewport.YOffset+n, 1, m.viewport.Height)
  }
@@ -361,9 +361,9 @@ func (m *Model) MoveDown(n int) {
  m.UpdateViewport()
 
  switch {
- case m.end == len(m.rows):
+ case m.end == len(m.rows) && m.viewport.YOffset > 0:
  m.viewport.SetYOffset(clamp(m.viewport.YOffset-n, 1, m.viewport.Height))
- case m.cursor > (m.end-m.start)/2:
+ case m.cursor > (m.end-m.start)/2 && m.viewport.YOffset > 0:
  m.viewport.SetYOffset(clamp(m.viewport.YOffset-n, 1, m.cursor))
  case m.viewport.YOffset > 1:
  case m.cursor > m.viewport.YOffset+m.viewport.Height-1: