From [Qt&#39;s documentation](http://qt-project.org/doc/qt-5.0/qtwidgets/qplaintextedit.html#details):

&gt; `QPlainTextEdit` is an advanced viewer/editor supporting plain text. It
&gt; is optimized to handle large documents and to respond quickly to user
&gt; input.
&gt; 
&gt; QPlainText uses very much the same technology and concepts as
&gt; `QTextEdit`, but is optimized for plain text handling.
&gt; 
&gt; `QPlainTextEdit` works on paragraphs and characters. A paragraph is a
&gt; formatted string which is word-wrapped to fit into the width of the
&gt; widget. By default when reading plain text, one newline signifies a
&gt; paragraph. A document consists of zero or more paragraphs. Paragraphs
&gt; are separated by hard line breaks. Each character within a paragraph
&gt; has its own attributes, for example, font and color.

And later on:

&gt; **Differences to QTextEdit**
&gt; 
&gt; `QPlainTextEdit` is a thin class, implemented by using most of the
&gt; technology that is behind `QTextEdit` and `QTextDocument`. Its performance
&gt; benefits over `QTextEdit` stem mostly from using a different and
&gt; simplified text layout called `QPlainTextDocumentLayout` on the text
&gt; document (see `QTextDocument::setDocumentLayout()`). The plain text
&gt; document layout does not support tables nor embedded frames, and
&gt; replaces a pixel-exact height calculation with a line-by-line
&gt; respectively paragraph-by-paragraph scrolling approach. This makes it
&gt; possible to handle significantly larger documents, and still resize
&gt; the editor with line wrap enabled in real time. It also makes for a
&gt; fast log viewer (see `setMaximumBlockCount()`).

So the difference is that `QPlainTextEdit` is optimized for handling plain text, and can be used even with very large plain text files. Also the way text is formatted is simpler.

If you plan to support only plain texts, then `QPlainTextEdit` is the right choice.

I am trying to have a fluid SVG canvas that can resize easily. So far I&#39;m using percentages everywhere. However it seems like SVG `polygon` and `path`s do not support percentages in `point` attribute. Here&#39;s an example: 

[(jsFiddle)](http://jsfiddle.net/yRbNH/)

    &lt;svg width=&#39;90%&#39; height=&#39;90%&#39; style=&#39;background-color: whitesmoke&#39;&gt;
        &lt;rect x=&#39;40%&#39; y=&#39;40%&#39; width=&#39;25%&#39; height=&#39;25%&#39; /&gt;

        &lt;polygon points=&quot;0,0 0,100 30,20 30,0&quot; /&gt;
        &lt;polygon points=&quot;30,0 30,20 60,0 60,0&quot; /&gt;
        &lt;polygon points=&quot;60,0 60,0 90,30 90,0&quot; /&gt;
    &lt;/svg&gt;


However if I start to change numbers in `points` attribute to percentages it fails with parsing error in console. I am looking for a way to have the polygon that can resize with the `&lt;svg&gt;` element.

SVG polygon points with percentage units support

I want to do this as easily as possible with out any additional libraries.

In my very long table I want to add a scrollbar to the `&lt;tbody&gt;` tag  so that the head is always visible but it wont work. can you please help.

fiddle : [http://jsfiddle.net/Hpx4L/][1]

    &lt;table border=&quot;1&quot;&gt;
      &lt;thead&gt;
        &lt;tr&gt;
          &lt;th&gt;Month&lt;/th&gt;
          &lt;th&gt;Savings&lt;/th&gt;
        &lt;/tr&gt;
      &lt;/thead&gt;
      &lt;tfoot&gt;
        &lt;tr&gt;
          &lt;td&gt;Sum&lt;/td&gt;
          &lt;td&gt;$180&lt;/td&gt;
        &lt;/tr&gt;
      &lt;/tfoot&gt;
      &lt;tbody style=&quot;overflow-y:scroll; height:100px;&quot;&gt; &lt;!-- wont work --&gt;
        &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
              &lt;tr&gt;
          &lt;td&gt;January&lt;/td&gt;
          &lt;td&gt;$100&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td&gt;February&lt;/td&gt;
          &lt;td&gt;$80&lt;/td&gt;
        &lt;/tr&gt;
      &lt;/tbody&gt;
    &lt;/table&gt;


  [1]: http://jsfiddle.net/Hpx4L/

add scroll bar to table body

What&#39;s the difference between `QTextEdit` and `QPlainTextEdit`, why use one over the other?

I&#39;m coding a text editor as an exercice to learn Qt5, and now I&#39;m wondering whether to use `QTextEdit` or `QPlainTextEdit`.
So far I&#39;ve only found out that you can display images in `QTextEdit`, but other than that they look somewhat identical to me.
My text editor should support some basic syntax highlighting (probably using `textChanged()` signal), but that&#39;s pretty much as far as the requirements go.

Google searches for *&quot;QTextEdit vs QPlainTextEdit&quot;* and *&quot;QTextEdit compared to QPlainTextEdit&quot;* didn&#39;t give me any decent results that would compare the two classes.

QTextEdit vs QPlainTextEdit

What's the difference between <code>QTextEdit</code> and <code>QPlainTextEdit</code>, why use one over the other?
I'm coding a text editor as an exercice to learn Qt5, and now I'm wondering whether to use <code>QTextEdit</code> or <code>QPlainTextEdit</code>.
So far I've only found out that you can display images in <code>QTextEdit</code>, but other than that they look somewhat identical to me.
My text editor should support some basic syntax highlighting (probably using <code>textChanged()</code> signal), but that's pretty much as far as the requirements go.
Google searches for "QTextEdit vs QPlainTextEdit" and "QTextEdit compared to QPlainTextEdit" didn't give me any decent results that would compare the two classes.

I don&#39;t understand when I should use `std::move` and when I should let the compiler optimize... for example:

    using SerialBuffer = vector&lt; unsigned char &gt;;

    // let compiler optimize it
    SerialBuffer read( size_t size ) const
    {
        SerialBuffer buffer( size );
        read( begin( buffer ), end( buffer ) );
        // Return Value Optimization
        return buffer;
    }

    // explicit move
    SerialBuffer read( size_t size ) const
    {
        SerialBuffer buffer( size );
        read( begin( buffer ), end( buffer ) );
        return move( buffer );
    }

Which should I use?

c++11 Return value optimization or move?

I&#39;m trying to use a `unique_ptr` to derived class in a function that takes a `unique_ptr` to a base class. Something like:

    class Base {};
    
    class Derived : public Base {};
    
    void f(unique_ptr&lt;Base&gt; const &amp;base) {}

    …

    unique_ptr&lt;Derived&gt; derived = unique_ptr&lt;Derived&gt;(new Derived);
    f(derived);

If I understand [this answer](https://stackoverflow.com/a/8114913/41071) correctly, this code should work, but it causes the following compile errors:

&gt; error C2664: &#39;f&#39; : cannot convert parameter 1 from &#39;std::unique_ptr&lt;_Ty&gt;&#39; to &#39;const std::unique_ptr&lt;_Ty&gt; &amp;&#39;
&gt;
&gt; IntelliSense: no suitable user-defined conversion from &quot;std::unique_ptr&amp;lt;Derived, std::default_delete&amp;lt;Derived&gt;&gt;&quot; to &quot;const std::unique_ptr&amp;lt;Base, std::default_delete&amp;lt;Base&gt;&gt;&quot; exists

If I change `f` to take `unique_ptr&lt;Derived&gt; const &amp;derived`, it works fine, but that&#39;s not what I want.

Am I doing something wrong? What can I do to work around this?

I&#39;m using Visual Studio 2012.

unique_ptr to a derived class as an argument to a function that takes a unique_ptr to a base class

I am developing an application using Qt. I don&#39;t know which slot corresponds to the event of &quot;the user clicking the &#39;X&#39;(close) button of the window frame&quot; i.e. this button:

![Close button of the window][1]

If there isn&#39;t a slot for this, can anyone suggest me some other method by which I can start a function after the user presses that close button.

  [1]: http://i.stack.imgur.com/rgFqm.png

Qt: How do I handle the event of the user pressing the &#39;X&#39; (close) button?

I have written a library that I used to compile using a self-written Makefile, but now I want to switch to cmake. The tree looks like this (I removed all the irrelevant files):

    .
    ├── include
    │&#160;&#160; ├── animation.h
    │&#160;&#160; ├── buffers.h
    │&#160;&#160; ├── ...
    │&#160;&#160; ├── vertex.h
    │&#160;&#160; └── world.h
    └── src
        ├── animation.cpp
        ├── buffers.cpp
        ├── ...
        ├── vertex.cpp
        └── world.cpp

So what I am trying to do is just to compile the source into a shared library and then install it with the header files.

Most examples that I have found compile executables with some shared libraries but never just a plain shared library.
It would also be helpful if someone could just tell me a very simple library that uses cmake, so I can use this as an example.

How to create a shared library with cmake?

Is it possible to develop a C++ program while using HTML and CSS for the user interface? I know about programming with Javascript using a Webkit container, but I am really interested in C++ development.

I felt in love with C# WPF when I developed under Windows, but now I moved to Linux and I haven&#39;t found a good tool for using markup for interfaces. For this, I would like to mix HTML and CSS, which are very lightweight and easy to use, with C++ code, with something like WPF.

Oh, one more thing: I&#39;m looking for desktop development, not web.

How to build native C++ apps with HTML/CSS UI?

I have a `QLabel` in my application that displays error messages to the user. I would like to make the text of the label selectable so users can copy and paste the error message if needed.

However, when I use the mouse to click and drag over the text, nothing happens - the text is not selected.

How can I make the text within a `QLabel` selectable by the mouse?

Make QLabel text selectable?

I just reinstalled QtCreator, created new project (*Qt Application*) an got this after compilation: 

    /usr/bin/ld: **cannot find -lGL**
    collect2: error: ld returned 1 exit status
    make: *** [untitled1] Error 1
    18:07:41: The process &quot;/usr/bin/make&quot; exited with code 2.
    Error while building/deploying project untitled1 (kit: Desktop Qt 5.1.0 GCC 32bit)
    When executing step &#39;Make&#39;

(*Project is empty, I did&#39;n commit any changes*)

&gt; Qt Creator 2.7.2  
Based on Qt 5.1.0 (32 bit)  
Ubuntu 13.04

How do I solve this problem?

Qt: can&#39;t find -lGL error

I am porting code from qt4 to qt5. I added the following line to my `.pro` file, [as suggested][1]:
  
    QT += webkitwidgets

However, when I run `qmake`, I get the this error:

    Project ERROR: Unknown module(s) in QT: webkitwidgets

I am developing on Ubuntu 12.04 LTS and installed Qt [as described][2].


  [1]: http://qt-project.org/wiki/Transition_from_Qt_4.x_to_Qt5
  [2]: https://askubuntu.com/questions/279421/how-can-i-install-qt-5-x-on-12-04-lts

Project ERROR: Unknown module(s) in QT: webkitwidgets

I want to code a notification window at the bottom right corner of the desktop, so it works like Skype notifications when someone comes online. Can someone help me get the screen size of the desktop, so I can place my notification window at the bottom right corner using my Qt Application?

How can I find the screen/desktop size in Qt, so I can display a desktop notification?

I am looking for a PyQt5 tutorial. It is rather complicated to start GUI development with Python for the first time without a tutorial.

I only found some PyQt4 tutorials so far, and since something changed from Qt4 to Qt5, for example the fact `SIGNAL` and `SLOT` are no more supported in Qt5, it would be nice to have specific tutorials for PyQt5.

Can someone please provide a tutorial on how to start GUI development with PyQt5?

Is there a tutorial specifically for PyQt5?

While debugging `C++` code in Qt creator I get the following error

    ptrace: Operation not permitted.
    
    Could not attach to the process. Make sure no other debugger traces this process.
    Check the settings of
    /proc/sys/kernel/yama/ptrace_scope
    For more details, see /etc/sysctl.d/10-ptrace.conf

Here a temporary solution is found: [Receiving error while trying to debug in QtProject][1]

 - temporary solution (won&#39;t survive a reboot):

     `echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope`


But it is difficult to run the same code in terminal every time when I start my PC to use Qt. 

    What is the permanent solution for this?

  [1]: https://askubuntu.com/questions/244336/receiving-error-while-trying-to-debug-in-qtproject


Qt Creator, ptrace: Operation not permitted. What is the permanent solution?

I see there is a new class for regular expressions - `QRegularExpression`. Is it just a typedef for QRegExp, or a new class, or what? And why do we need it, we already have QRegExp?

Content Type	Original Author	Original Content on Stackoverflow
Question	Markus Meskanen	View Question on Stackoverflow
Solution 1 - C++	Bakuriu	View Answer on Stackoverflow

QTextEdit vs QPlainTextEdit

C++ Problem Overview

C++ Solutions

Solution 1 - C++

add scroll bar to table body

SVG polygon points with percentage units support

Attributions