X11 Graphical Desktop

Hint

In addition to using X11 Desktops in your Project, you can also run JupyterLab, VS Code, X11 Desktop on Compute Servers.

CoCalc is a modern web-application, but there are many already existing desktop applications. This aspect of CoCalc brings such applications to the web, by running them inside a minimal graphical environment and presenting them to you via the browser. It is even possible to collaboratively work on the same application – although be warned that this is quite confusing!

See this blog post for more screenshot and further explanations.

Getting started

In your project, create an X11 Desktop-file (which has the ending *.x11), or use the corresponding button when creating a new file. You should see a split frame editor with

• on one left side:

  • a Linux Terminal and

  • launcher buttons for starting applications

• On the right hand side, there is the view area for X11 windows

Initially, that X11 area is empty and you have to start an application. To get started, we suggest to launch a simple text editor like Gedit or LibreOffice Writer.

Note

You need to click once on the X11 window in order to focus it. This tells it to process any input (mouse clicks, keyboard characters, …)

In the screenshot below, you can see that gedit was typed into the Linux Terminal. After hitting the return key, the application was launched and the window is shown. The characters “asdf” were typed in and then the “Save”-Button at the top right inside the Gedit windows was pressed. This opened up an overlay dialog window. There, type in the filename and click “Save” at the bottom again.

Afterwards, this did create a file named file1.txt in the current directory. Go ahead and open it up inside of CoCalc!

Overlay Dialogs

Modal dialogs open up as almost-maximized windows on top of the current window of the application.

Note

An overlay dialog window without a Close, Ok, or Cancel button can be closed by clicking on the application visible in the background; i.e. the surrounding area of the dialog.

Window Tabs

When you open up multiple applications (or a single application opens multiple windows), they appear as tabs at the top of the X11 view area. In the screenshot below, you can see that the text file was also opened up in LibreOffice Writer:

Note

Sometimes, applications open up additional dialog windows, which show up as tabs at the top. In order to respond to the application’s dialog window, you have to click on the appropriate tab to open it up and take appropriate actions. (e.g. confirming a certain operation, etc.)

Keyboard Layout

CoCalc will try (badly) to guess your keyboard layout based on your browser’s default language settings. This does NOT work well. Instead, you should explicitly select your keyboard layout in Account preferences:

1. Open up your Account Settings

2. In the tab “Preferences”, look for the panel “Editor settings”

3. Inside “Editor Settings”, look for Keyboard layout (for X11 Desktop)

Note

Many languages like “German” will only work well with the variant “no dead keys”.

Zoom

CoCalc tries to match its virtual desktop size to the size of the frame inside your browser window. It will also calculate an appropriate zoom level based on the resolution of your screen. However, this might not always work.

At the top of the X11 area are zoom controls, which allow you to change the resolution. Sometimes, it might also be necessary to change some settings within the application itself (some zoom related ones in its preferences), or to change the size of the panel or browser window itself. CoCalc dynamically resizes the desktop and the application will redraw accordingly.

Terminal

Inside the small Linux Terminal on the side, you can run programs or your own scripts. For example, this could be a Python script, or even a full application: try this matplotlib: Embedding In Wx5 example.

Behind the scenes, after the X11 environment starts up, the $DISPLAY variable is set to tell the application where to show the graphical window. Please wait until it is initialized, which you can see after the connection indicator at the top right next to “X11” vanishes. Otherwise, you’ll get this error message Unable to access the X Display, is $DISPLAY set properly?.

Example script (you can also run it interactively in an ipython3 shell):

import matplotlib
matplotlib.use('wxAgg')
import numpy as np
import matplotlib.pyplot as plt
plt.plot(np.random.randn(1000).cumsum())
plt.show()

Technical Status

• Desktop (works well):

  • Chrome version 66+ is fully supported

  • Copy does not work on Firefox or Safari

• Mobile (does NOT work):

  • Viewing the desktop should mostly work

  • Touch events barely work at all.

  • Even an external keyboard will NOT work on an iPad (keys will be stuck, etc.).

Installed Applications

Note

Unless otherwise noted, the application’s name is also the command to start the executable. For most applications you can find a launcher button:

Name	Description	Category	Status
auctex		latex	?
avogadro	Advanced molecule editor and visualizer	chem	OK
blender	3D graphics (to visualize wireframes)	graphics	OK
cadabra2-gtk	A field-theory motivated approach to computer algebra	physics	OK
code	Visual Studio code	code	OK
darktable	photography workflow application and raw developer	paint	OK
google-chrome	Chrome Web-browser	web	Randomly crashes due to Docker security requirements
dia	Drawing graphics	graphics	Mostly OK
emacs	Powerful text editor, code, and everything else	code, text	OK
firefox	Web-browser	web	Crashes
gchempaint	Draw chemical formulas (no single-window mode, though)	chem	?
gedit		text	OK
gitk	Explore a Git repository (in current directory)	git	OK
gitg	Simplified interface for working with Git	git	OK
gimp	Draw and edit images. (make sure to switch to “single window mode” in the “Window” menu)	paint	OK
gnome-calculator	Classical calculator	math	OK
gnumeric	Spreadsheet calculations and statistics	stats	OK
gschem	schematic capture program/tool part of gEDA	physics	OK
gvim	Graphical version of the famous VIM editor	text	OK
idle	Minimalistic Python IDE	code	OK
inkscape	Professional vector graphics editor	graphics	OK
jedit	Java-based text editor	text	?
kbibtex	Reference management software primarily for BibTeX	latex	OK
kexi-3.1	Microsoft Access for Linux	db	OK
kile	LaTeX editor, but probably use texmaker instead …	latex	OK
krita	Painting tool designed for concept artists	paint	OK
latexdraw	Draw PSTricks, etc.	latex, graphics	flickers :-(
libreoffice	Office suite consisting of: localc, lowriter, loimpress, lobase, …	office	OK
lyx	LyX combines the power and flexibility of TeX/LaTeX with the ease of use of a graphical interface.	latex	OK
meld	a visual diff and merge tool targeted at developers	code	OK
nteract	Jupyter Notebook compatible UI	calc	OK
octave	Octave	calc	OK
okular	PDF reader and annotator (Tools → Review)	pdf	OK
OpenModelica	Modeling and simulation environment. Command: OMEdit & co.	physics	OK
pcb-gtk	printed circuit board editor	physics	OK
pinta	simple paint app for images	paint	OK
psppire	PSPP is an open-source version of SPSS	stats	OK
RCommander	graphical UI for R: start by require(Rcmdr)	stats	OK
rstudio	Open source R IDE. On high resolution displays set Tools → Global Options → Appearance → Zoom → 200%	stats	OK
scribus	a page layout program	office	OK
SnapPy in Sage	Run via sage -python -m snappy.app	math	Arrow keys
spyder3	a powerful scientific environment for Python	math	OK
texmacs	LaTeX editor	latex	OK
texmaker	Powerful, easy to use and elegant LaTeX editor	latex	OK
texstudio	Make writing LaTeX as easy and comfortable as possible	latex	OK
thunderbird	Email client	office	OK
tikzit	A super simple GUI editor for graphs and string diagrams	latex, graphics	?
tuxpaint	Children’s paint program	paint	OK
wxmaxima	Computer algebra system Maxima	math	OK
xedit	Old graphical text editor in X	edit	OK
xournal	Draw notes or annotate a PDF	pdf	OK
xpaint	Old paint program	paint	OK

Categories

Category	Description
math	mathematics
chem	chemistry applications
stats	statistics, data analysis, …
physics	tools for physics, engineering, modeling, etc.
office	productivity apps for authoring text, presentations, spreadsheets, etc. (doc, docx, odt, ppt, xml, xmlx, ods, …
latex	editor for working with LaTeX documents
text	general purpose text editors
code	tools for software development (IDE, etc.)
git	working with Git
db	graphical database interfaces
paint	raster graphics editor
graphics	vector graphics editor
pdf	for reading, editing, annotating PDFs

Tips & Tricks

High-resolution HDPI displays

If the visible buttons/controls are small, especially if you have a high-res display, and zooming alone doesn’t really help much, enable HDPI rendering. That’s available for some of the applications in their respective configuration dialogs.

In R IDE you can go to Tools → Global Options → Appearance → Zoom → 200%.

In Spyder Enable auto high DPI scaling option is available via the Tools > Preferences menu or the wrench-icon:

Enable auto high DPI scaling in Spyder

Is Scilab broken?

In theory, Scilab should work in this X11 Graphical Desktop editor, but there is a long standing issue in Ubuntu Linux about this.

As of May 2019, it works, but maybe it’s broken again ¯\_(ツ)_/¯ ?