code: func (cb *CellBuffer) SetContent(x int, y int,
  	mainc rune, combc []rune, style Style) {
  
  	if x >= 0 && y >= 0 && x < cb.w && y < cb.h {
  		c := &cb.cells[(y*cb.w)+x]
  
  		c.currComb = append([]rune{}, combc...)
  
  		if c.currMain != mainc {
  			c.width = runewidth.RuneWidth(mainc)
  		}
  		c.currMain = mainc
  		c.currStyle = style
  	}
  }
docs: // SetContent sets the contents (primary rune, combining runes,
  // and style) for a cell at a given location.