Ctrl Shift . and Ctrl Shift , shortcuts move focus to the next and previous tab bar in the main area, respectively (#7673)
Shift Home and Shift End shortcuts in a notebook select all cells from the current cell to the top or bottom of a notebook, respectively (#7177)
Explicit "No Kernel" button in the kernel selection dialog for new notebooks (#7647)
Notebook recordTiming advanced setting to control whether execution timing information is stored in notebook files (#7578)
"Select current running or last run cell" command added (requires notebook recordTiming advanced setting to be set to true) (#7551)
Codemirror lineWiseCopyCut advanced setting to control the behavior of the copy/cut keyboard shortcuts when there is no selection (#7842)
Refreshed the command palette and property inspector sidebar icons and user interfaces (#7577, #7038, #7733, #7732, #7718, #7686)
"New File" and "New Markdown File" items in file browser context menu (#7483, #4280)
"Download" item in File menu (#7480)
"Restart Kernel and Run up to Selected Cell" item in notebook Kernel menu (#7789, #6746)
In extension manager, the "enable" button is now only shown for installed extensions (#7482)
Dialogs can now be closed by clicking outside of them (#7885, #3784)
documentsearch:startWithReplace command to open the document find overlay with replace. There is not currently a default keyboard shortcut for this, but one can be assigned as a custom keyboard shortcut in Advanced Settings. (#7725)
# added to the CSV Viewer delimiter options (#7367, #6324)
The JSON viewer now only displays structure hints for arrays and empty objects for a more streamlined feel (#7227)
Optional platform-aware keyboard shortcut fields linuxKeys, macKeys, and winKeys in keyboard shortcut definitions (#7589)
```
{
  command: "application:toggle-mode",
  selector: "body",
  linuxKeys: ["Ctrl Shift M"], // only linux
  macKeys: ["Cmd Shift Z"], // only mac
  winKeys: ["Ctrl Shift B"], // only windows
  keys: ["Accel Shift U"] // default shortcut
}
```
Added options for jupyter lab clean to clean specific parts of the build, such as --extensions, --settings, --static, and --all (#7583, #6734)
Removed the vega 4 and vega-lite 2 renderers (vega 5 and vega-lite 4 is included in JupyterLab by default). These legacy renderers may be available via custom extensions (#7650, #7523, #7658)
JupyterHub users should use the c.Spawner.default_url = '/lab' setting instead of the deprecated and now removed labhubapp (#7724)

For developers

See extension_migration for help in migrating extensions to JupyterLab 2.0.

Backward incompatible changes

Switch from @phosphor to @lumino dependencies. (#7582, #7534, #7763, #7762, #7595)
Factor out the settingsregistry and statedb packages from coreutils (#7681, #7615)
Rework services architecture (sessions, kernels, terminals). Among these changes, ClientSession is renamed to SessionContext and the IKernelConnection.connectToComm method is replaced with IKernelConnection.createComm and IKernelConnection.hasComm methods. (#7252, #7674, #7820, #7694, #7690, #7682)
Upgrade to TypeScript 3.7 (#7522)
Remove polling from coreutils in favor for @lumino/polling (#7617)
TypeScript strict null checking in core packages (#7657, #7607)
Update state database list method to query based on namespace match. (#7742, #7257)
Address code todo items and deprecations for 2.0 (#7720, #7724)
Update Console panel tracker widgets (#7705, #7726, #7648, #7645)
Update contribution guide to require node v12+ (#7479)
New API for the Running sidebar extension (#6895, #6876)
Clean up handling of icons under unified LabIcon ( #7192 #7700, #7765, #7767, #7800, #7846, #7859, #7864, #7886)

Other changes

New property inspector used to display the properties of the currently selected main area widget (#7665, #7664, #7718, #7686)
Allow metadata for launcher items (#7654, #7652)
Allow default file browser to restore manually. (#7695, #4009)
Upgrade bundled yarn to 1.21.1 (#7691, #7692)
Make session dialogs configurable (#7618, #7616)
Support transient editor configs (#7611, #7295)
Optionally force new browser tab (#7603, #7602)
Update core dependencies (e.g., codemirror, xterm.js, markdown, fontawesome, etc.) (#7590, #7194, #7326, #6479, #7769)
Add storybook to ui-components (#7588, #6799)
Add explicit documentation encouraging people to re-use lab components (#7543)
Enable TypeScript sourcemaps for debugging locally installed labextensions (#7541)
Add UseSignal example to the docs (#7519)
Add env prop to kernel options (#7499)
Add kernelspec metadata (#7229, #7228)
Allow different mimetypes for the clipboard data (#7202)
Add password dialog to apputils (#7855)
Alias phosphor packages to lumino to allow a deprecation period for phosphor (#7893)
Match react version in ui-components peerdependencies (#7794)
Fix lint-staged for both win and mac (#7784)
Update websocket workaround for node environments (#7780, #6934)
Fix handling of linked extensions (#7728, #6738)
Fix extension compatibility checks for prereleases and extensions supporting multiple major versions of JupyterLab (#7723, #7241, #7919)
Teach update-dependency about more range specifiers and make it adopt the current range for any tag (#7709)
Add support for giving a rank to items in the top area (#7278)
Apply all options to the initial JupyterLab application instance (#7251)

Bugfixes

"Copy Shareable Link" in the file browser context menu now properly works in JupyterHub (#7906)
Update Mathjax CDN in the cell and console examples (#7680)
Revert ensure-max-old-space now that Node 12+ has better default memory ceilings (#7677, #7675)
Resolve race condition between default file browser and tree urls. (#7676, #4009)
Fix handling of code editor refresh (#7672, #7671)
Start new notebooks in edit mode (#7666, #6731)
Use consistent versions of React (#7661, #7655)
Add scrollbar styles to nbconvert-css (#7653)
Close output views when corresponding notebooks are closed (#7633, #7301)
Fixed incorrect white background for new command palette icon (#7609, #7577)
Block fetching the settings for a plugin that is disabled (#7147)
When timing metadata changes, ensure signal fires (#7576)
Prevent memory leaks in Vega renderer (#7564)
Handle cell execution cancellation when cell is disposed (#7555, #7554)
Fix dropdown option style issue on Windows (#7513)
Make sure label is linked to a control when checking for element type (#7458)
Refine log console message UX (#7448, #7444, #7443)
Fix multicursor backspacing (#7401, #7205)
Reset log display and count when non-notebook tab gets activated (#7334, #7325)
Fix Safari multiple tabs by working around a Safari bug. (#7316, #6921)
Skip custom click behavior on links when the download attribute is set (#7311, #5443)
Fix context menu hit test to deal with SVG nodes. (#7242, #7224)
Fix overwriting of target attribute of anchors rendered by IPython.display (#7215, #6827)
Fix file browser location in tree view (#7155)
Stop too many fetch calls in docmanager-extension (#7879, #7874)
Ensures that Shift Tab dedent shortcut works correctly in the file editor (#7865)
Fix unexpected jump to last search result when using documentsearch (#7835)
Fixed refresh issue for html viewer (#7824, #7552)
Fix for center-aligned images with IPython.display.image (#7798)
Changes to setting editor should trigger application dirty state (#7774, #7757)
Move vega from "devdependencies" to "dependencies" (#7699, #7689)
Restore default file browser manually. (#7695, #4009)
Use default app_dir when app_dir is '' (#7268, #7264)