atom/packages/one-dark-ui/lib/main.js

const root = document.documentElement
const themeName = 'one-dark-ui'

module.exports = {
  activate (state) {
    atom.config.observe(`${themeName}.fontSize`, setFontSize)
    atom.config.observe(`${themeName}.tabSizing`, setTabSizing)
    atom.config.observe(`${themeName}.tabCloseButton`, setTabCloseButton)
    atom.config.observe(`${themeName}.hideDockButtons`, setHideDockButtons)
    atom.config.observe(`${themeName}.stickyHeaders`, setStickyHeaders)

    // DEPRECATED: This can be removed at some point (added in Atom 1.17/1.18ish)
    // It removes `layoutMode`
    if (atom.config.get(`${themeName}.layoutMode`)) {
      atom.config.unset(`${themeName}.layoutMode`)
    }
  },

  deactivate () {
    unsetFontSize()
    unsetTabSizing()
    unsetTabCloseButton()
    unsetHideDockButtons()
    unsetStickyHeaders()
  }
}

// Font Size -----------------------

function setFontSize (currentFontSize) {
  root.style.fontSize = `${currentFontSize}px`
}

function unsetFontSize () {
  root.style.fontSize = ''
}

// Tab Sizing -----------------------

function setTabSizing (tabSizing) {
  root.setAttribute(`theme-${themeName}-tabsizing`, tabSizing.toLowerCase())
}

function unsetTabSizing () {
  root.removeAttribute(`theme-${themeName}-tabsizing`)
}

// Tab Close Button -----------------------

function setTabCloseButton (tabCloseButton) {
  if (tabCloseButton === 'Left') {
    root.setAttribute(`theme-${themeName}-tab-close-button`, 'left')
  } else {
    unsetTabCloseButton()
  }
}

function unsetTabCloseButton () {
  root.removeAttribute(`theme-${themeName}-tab-close-button`)
}

// Dock Buttons -----------------------

function setHideDockButtons (hideDockButtons) {
  if (hideDockButtons) {
    root.setAttribute(`theme-${themeName}-dock-buttons`, 'hidden')
  } else {
    unsetHideDockButtons()
  }
}

function unsetHideDockButtons () {
  root.removeAttribute(`theme-${themeName}-dock-buttons`)
}

// Sticky Headers -----------------------

function setStickyHeaders (stickyHeaders) {
  if (stickyHeaders) {
    root.setAttribute(`theme-${themeName}-sticky-headers`, 'sticky')
  } else {
    unsetStickyHeaders()
  }
}

function unsetStickyHeaders () {
  root.removeAttribute(`theme-${themeName}-sticky-headers`)
}