I can't make a screencast.  The options in my login screen didn't work so I edited  /etc/gdm3/custom.conf    by deleting the # before WaylandEnable=false using terminal, and saved the file.  The error remains, even after restarting my laptop.  When I press Ctrl+Alt+Shift+R to start recording what is on my screen it just open this link and NO recording.  When I use the VLC App to record my screen it gives me this error     Your input can't be opened:   VLC is unable to open the MRL 'screen://'. Check the log for details.
After upgrading to Ubuntu 17.10 I noticed some of my screencasting applications are not working, for example screencasting tools like SimpleScreenRecorder and vokoscreen. ()  Also I noticed features like screenshot from GIMP is not working properly, producing blank screenshots (). Shutter too is producing glitchy screenshots ().  Screen-sharing option on Skype is also not working ().  The issue occurs sometimes on later Ubuntu releases too.  Why is this happening and how do I fix this?
How to get the list of predefined colors in xcolor such that the list can be used in foreach looping? How exactly was the finalist chosen in the NIST AES competition? Restore Macintosh HD to its original partition configuration I am new to QGIS. I am looking for any plugin or any manual method in QGIS for finding minimum distance (perpendicular distance) from a point which is part of one shapefile to nearest line among many lines which is part of another shapefile.   MMQGIS is not useful for this purpose. Why aren't there any common words for 'defecating' and 'urinating'? When should I use the subjunctive mood? In which cases should I use the subjunctive mood?     I suggest that every applicant fill out the form carefully.        If she were rich, she would live on Long Island. How can I use JUnit4 idiomatically to test that some code throws an exception?  While I can certainly do something like this:  @Test public void testFooThrowsIndexOutOfBoundsException() {   boolean thrown = false;    try {     foo.doStuff();   } catch (IndexOutOfBoundsException e) {     thrown = true;   }    assertTrue(thrown); }   I recall that there is an annotation or an Assert.xyz or something that is far less kludgy and far more in-the-spirit of JUnit for these sorts of situations. Prove that $\liminf x_n = -\limsup (-x_n)$ How can we prove that $\liminf x_n = -\limsup (-x_n)$?  The definitions we are using are $\limsup x_n = \lim\limits_{n\to\infty} \sup\{x_k; k\ge n\}$ $\liminf x_n = \lim\limits_{n\to\infty} \inf\{x_k; k\ge n\}$ Expandably change letter case and use inside \csname, without a package I want to change the letter-case of a single character argument, and use that changed letter inside a \csname.  And I want to do it without an additional package.  For example, I want to pass a macro the letter {S}, and have it execute the macro \csname macros\endcsname, or pass it the letter {T}, and have it execute the macro \csname macrot\endcsname.    In my MWE, I show three approaches:   I didn't expect \lowercase to work, since I recall reading that it is not truly expanded until the last possible moment.  Surprisingly, it goes into an \edef okay, but it must not be truly expanded, because it breaks the \csname. I also formulated an approach where I used \numexpr to add 32 to the ASCII code of the argument and perform a \char upon that result.  Like \lowercase, it gives the appearance of being expandable, but it also fails inside the \csname. I finally achieve success with the stringstrings package.  Having written the package, I know the conversion was not pretty... essentially, it is an exhaustive 26-fold check of the form \if #1Aa\else\if #1Bb\else\if #1Cc\else...\fi\fi\fi, which has the virtue that it can be expandably placed into an \edef, and so it works.   There has to be a better way.  The MWE works only because I use the inefficiently calculated \tmp from METHOD 3 inside the \csname.  If I use \tmp from either of the two earlier methods, it breaks.  \documentclass{article} \usepackage{stringstrings} \def\macros{Expandably converted an S to a s} \def\macrot{Expandably converted a T to a t} \newcommand\convert[1]{%   %MAKE THE ARGUMENT LOWER CASE   1) LOWERCASE\\   \edef\tmp{\lowercase{#1}}% PRETENDS TO EXPAND, BUT FAILS IN \csname   Here is the ``expanded'' conversion: \tmp\\   % OR   2) ASCII CONVERSION\\   \edef\tmp{\expandafter\char\numexpr`#1+32\relax}% PRETENDS TO EXPAND, BUT FAILS IN \csname   Here is the ``expanded'' conversion: \tmp\\   % OR   3) STRINGSTRINGS PACKAGE\\   \caselower[q]{#1}\def\tmp{\thestring}% WORKS BUT USES A PACKAGE   Here is the ``expanded'' conversion: \tmp\\   %   Now use it in a csname: \csname macro\tmp\endcsname% } \begin{document} \convert{S}\par \convert{T} \end{document}       SUMMARY OF ANSWERS:  I have added egreg's code snippets into this MWE to produce a document (and not just terminal output), showing the methods put forth to this point:  \documentclass{article}  %%%%%%%%%%%%%%%%%%%%%%%%%%%% L3 APPROACH  \usepackage{expl3}  \ExplSyntaxOn \cs_set_eq:NN \Xexplower \tl_expandable_lowercase:n \ExplSyntaxOff  %%%%%%%%%%%%%%%%%%%%%%%%%%%% EGREG'S LESS HACKY SOLUTION  \def\explowerchar#1{%   \ifcase\numexpr`#1-`A\relax    a\or b\or c\or d\or e\or f\or g\or h\or i\or j\or k\or l\or m\or    n\or o\or p\or q\or r\or s\or t\or u\or v\or w\or x\or y\or z\else    #1\fi }  \def\explower#1{%   \doexplowerchar#1\relax }  \def\doexplowerchar#1{%   \ifx#1\relax   \else     \explowerchar{#1}\expandafter\doexplowerchar   \fi }  %%%%%%%%%%%%%%%%%%%%%%%%%%%% STEVE'S HACKY PACKAGE APPROACH  \usepackage{stringstrings}  %%%%%%%%%%%%%%%%%%%%%%%%%%%%  \def\macros{Expandably converted an S to a s} \def\macrot{Expandably converted a T to a t}  \begin{document}  \textbf{Steve's hacky approach}  \caselower[q]{S}\csname macro\thestring\endcsname\par \caselower[q]{T}\csname macro\thestring\endcsname  \textbf{egreg's less hacky approach}  \edef\lcstring{\explowerchar{S}}\csname macro\lcstring\endcsname\par \edef\lcstring{\explower{T}}\csname macro\lcstring\endcsname  \textbf{L3 approach}  \edef\lcstring{\Xexplower{S}}\csname macro\lcstring\endcsname\par \edef\lcstring{\Xexplower{T}}\csname macro\lcstring\endcsname  \end{document} Best way to reward an exceptionally good answer Have you ever gotten an answer soooo good, you wished you could give a +20 instead of +1 ?  Bounty System  That's a good mechanism, but they're not always right for this situation:   Bounties are usually associated with giving incentive to answer or draw traffic. I would expect that most users offered bounties before getting an answer, not after. Bounties are usually offered by people with plenty of reputation. "New" users should be able to reward exceptional answers too.   Thanking in a comment  A warm comment on the answer is always nice, but I'm not sure comments are intended for saying thanks - but to clarify / improve the answer itself.  So what is the recommended way to reward this truly exceptional answer?  Other suggestions?  I know there is an answer of the week blog, is there a way to nominate an answer to be there? Sometimes exceptional answers are hidden in low-interest questions that receive less traffic - so those will never be upvoted enough to become noticed.  Or maybe instead of a single blog for the entirety of SO, there should be an entire section called "Answer of the week" with more than one answer (maybe on a per-tag basis). Answers should arrive there based on manual nominations and not on upvotes so unpopular questions will not be discriminated against.  Clarification:  It's not that I'm personally against bounties - I use them plenty of times. I'm mostly concerned about what other people tend to do. I suspect the bounty post-answer reward is not used as much as it should. I believe the majority of people don't consider bounties for this purpose. Where is "Connect to Server" for ssh connections in Unity? Cannot find "connect to server" in 11.04, looks like unity doesn't have it. Is there other very similar way to connect to another Ubuntu computer via SSH? (not in terminal) Sum of two closed sets in $\mathbb R$ is closed? Is there a counterexample for the claim in the question subject, that a sum of two closed sets in $\mathbb R$ is closed? If not, how can we prove it?  (By sum of sets $X+Y$ I mean the set of all sums $x+y$ where $x$ is in $X$ and $y$ is in $Y$)  Thanks! My chain broke and in a moment of silliness (I was cold wet and slightly annoyed)  I threw the broken one away before thinking about measuring the new one.  Is there a guide to getting the chain length/tension correct ?  It's an 8 speed road bike (Shimano Sora back, double ring front) I am about to start a web project and have been working almost exclusively with a LAMP stack for the past 5 years.  I would like to build something larger and more scalable and hence have been looking into Java EE.  The division of logic between JSP and EJB seems ideal for what I want to do.  Can anyone recommend resources for getting familiar with Java EE?  And perhaps if anyone knows of technologies that are more scalable than PHP that I should consider as well, I'm all ears.  Thanks a lot! Photoshop: How to draw a guide with an exact distance from another guide Before drawing, I want to draw all guides for my layout. For example, I have a guide line named A already. After that, I want to have another guide named B  parallel with guide A and at 50px distance from it.   I have three solutions:   Draw line B and by "some way", I can see the current distance directly when I'm drawing, so I can make the distance exactly what I want it to be.  Draw line B. And then I use the Ruler tool to see the distance between the two guides. This method has disadvantages: maybe the ruler line that I draw isn't perpendicular with the guides and I'm not sure when the distance is enough. There are other clever ways, that help me get this job done fast and easily, but that I don't know yet. I think Photoshop should support this feature.   What is the best way to achieve this? I have a huge amount of 2D-coordinates, associated with a value, e.g.:    x   |   y   | value 27.50   52.15   12.51 61.83   13.32   57.56 36.23   21.83   41.73 40.46   85.67   25.20 ...   The data is not tabular and I Want the points between two data-points to be interpolated in some way (which way is not really clear, yet)  I want to preset the data as heatmap like this:   Is there any ready-to-use package for PSTricks or TikZ to do it? Detecting significant predictors out of many independent variables In a dataset of two non-overlapping populations (patients &amp; healthy, total $n=60$) I would like to find (out of $300$ independent variables) significant predictors for a continuous dependent variable. Correlation between predictors is present. I am interested in finding out if any of the predictors are related to the dependent variable "in reality" (rather than predicting the dependent variable as exactly as possible). As I got overwhelmed with the numerous possible approaches, I would like to ask for which approach is most recommended.    From my understanding stepwise inclusion or exclusion of predictors is  E.g. run a linear regression separately for every predictor and correct p-values for multiple comparison using FDR (probably very conservative?) Principal-component regression: difficult to interpret as I won't be able to tell about the predictive power of individual predictors but only about the components.  any other suggestions? Convert .bbl file to .bib file How can I convert a .bbl file to a .bib file. I  lost my .bib file but I still have my .bbl file. Now , I need to add more references to my .bbl file according to a specific format which I need to produce using Bibtex, so how can I convert my .bbl file to a .bib file so I can add the new references according to the format.  Thanks for any insight. How to prevent upper case in page header? I just came across this small problem which I can't seem to fix. I have a section which looks like this:  \section{Properties of $C_q$}   The problem is that the header of the page uses upper case and so it displays this section title as if I had written  \section{Properties of $C_Q$}   How can I make sure the q is always lower case? Graph theory: Tree holds two sub-tree with an amount of vertices