All posts by PCMan

Build lxde-qt from git source: an updated guide

Since the original LXDE and razor-qt projects decided to merge the effort and work together on the same project, we formed lxde-qt, or lxqt for short. Some effort was made to merge existing codebases and components, but things are still in an early stage so there is no public release yet. For preview purpose, here is a guide for the brave to build lxde-qt from git source code. Please note, since this is a work in progress, things are subject to frequent changes. So be prepared and don’t expect too much. Things will improve, but it takes time. :-)

Please don’t use it in a production environment. It’s not ready for daily use yet. You have been warned.

Obconf (Openbox Config Tool) is ported to Qt

Since we’re using Openbox as our default window manager, we need a GUI way to configure it. Previously, we have a GUI config tool for OpenBox named obconf, which is based on gtk+ 2 and libglade. However, since we plan to use Qt, and gtk+ 2 is no longer officially supported by its upstream, a Qt port is wanted.
Hence, as part of LXDE-Qt project, I started a Qt port of obconf and that’s obconf-qt.
It’s a pure Qt program so it works as well outside LXDE-Qt. It’s also useful for the upcoming razor-qt 0.6.

Please test the source code in git:
> git clone git://----escape_autolink_uri:5acf69934b3dbf516eae5a6e8c914e7f----

Or, browse the code online:;a=summary

Most of the original features are already been ported to Qt.
What still does not work:
1. font settings.
2. dock settings.
3. preview of themes
Other stuff should work as expected.

If anyone is willing to help, please contact me.
Thank you.

No, LXDE-Qt is not bloated

After posting a preview screenshot for LXDE-Qt, I got quite a lot of feedback from various sources. Generally the responses from the users are positive, but there are also some people saying that LXDE is no longer lightweight.

Please, in the free world we’re all friends and let’s not spread FUDs to hurt each other. I’m not going to respond to groundless accuse or get involved in toolkit wars. Just see the screenshot.

This screenshot is done for a cleanly installed Debian testing system running LXDE-Qt after a cold boot. The Qt theme engine used is “CleanLook”.

The command “free -h” shows that 252 MB is in use. However, most of the space is used for buffers and caches. After excluding caches and buffers, the memory usage is 91 MB. On the same machine, LXDE gtk+ version uses 86 MB. Will you call this “bloated”? Please note that I open “lxterminal”, a GTK+ 2 terminal emulator, to execute the “free” command. That means doing this also loads GTK+ so the actual memory usage should be lower than this. Besides, I’m using zh_TW locale since I’m from Taiwan and we use traditional Chinese here. That means, I also have Chinese fonts and input methods loaded in the memory. If you’re a western user, you probably don’t need them and can save a little bit here.

By default, similar setting under Ubuntu will use around 200 MB of RAM.  That’s caused by differences between distros, not the bloat of LXDE. So, please stop spreading unfounded FUDs. Qt is designed for use with embedded systems and cell phones. How fat and resource hungry can it be? It’s the way you use it that really matters.

Delivering a good lightweight desktop is always our goal no matter what approach we’re using. So stay tunned and be confident.

LXDE-Qt Preview

Many users have read about our recent Qt-related work in prior blog posts.
The GTK+ version of LXDE is still under development, but we did some experiments with Qt, too. Now I have some things to show you. :-)
Here is a preview screenshot for LXDE-Qt.

At the bottom of the screen is lxpanel-qt, the Qt port of lxpanel. Now it basically works, but it’s still rough and needs much polishing. Besides, there are no GUI configuration tools for it yet. Editing the xml config file manually is needed. Later there will be preferences dialogs as the old gtk+ version of lxpanel. Most of the major applets already work. However, don’t expect too much!
It’s still a work in progress and it can be better in the future.

In the middle of the screen is PCManFM-Qt, the Qt port of the PCManFM file manager. It looks very similar to the original gtk+ version. The desktop wallpaper and icons are also managed by PCManFM-Qt, just like what the gtk+ version does.
The memory usage of PCManFM-Qt is slightly higher than that of the gtk+ 2 version, but the difference is not very significant. The overall performance is similar to the original gtk+ 2 version. Now it has most of the features of the original one and is almost ready for daily use. \o/

On the right side of the screen is the new Qt-based image view, LxImage-Qt.
It’s not really a port of the original gtk+ GPicView. I regard it the successor of GPicView in the Qt world. It works better than GPicView and is as fast.

Most of the work demonstrated in the screenshot is still in our git repository and is not ready for a new stable release, but there is really much progress and LXDE-Qt is no more a plan or a concept. It’s a real project that gradually shapes.

OK, back to what most user will concern, the resource usage.
To be honest, migrating to Qt will cause mild elevation of memory usage compared to the old Gtk+ 2 version. Don’t jump to the conclusion too soon. Migrating to gtk+ 3 also causes similar increase of resource usage.
Since gtk+ 2 is no longer supported by its developer and is now being deprecated, porting to Qt is not a bad idea at the moment.
Besides, the slightly higher memory usage is still acceptable for most of the existing old machines. The real resource usage may differ a lot among different Linux distros. For example, Ubuntu-based distros running LXDE tends to use more memory than ArchLinux-based ones. So more testing and real benchmarks are needed before making a conclusion on this.

Anyway, glad to share with you what we already done. Hope that you like it. :-)
Long live LXDE!

Edited on 2013-07-04
Answer the questions in the comments of this blog entry:

  1. Cooperation with razor-qt is going on. We subscribed razor-qt google groups and discussed about possible cooperation earlier. Currently, the ported LXDE components are designed with Razor-Qt in mind. For example, PCManFM-Qt and LxImage-Qt will reads razor-qt config file when running in razor-qt session. We’ll try to keep the interchangeability between the two DEs. Further integration is also possible. Actually, I personally am running a mixed desktop with LXDE-Qt + Razor-Qt components on my laptop. Components from the both DE blends well.
  2. The version of Qt supported now is Qt 4. I’m going to skip Qt 5 and wait for Qt 5.1. Qt4 and Qt5 are compatible in many areas and porting to Qt5 should be easy in most of the cases. Unfortunately, this is not the case when you use X11-related stuff. Qt 5 removed many X11-related APIs and there are no direct equivalent methods. So the porting is not painless for desktop environments. In addition, some specs are designed to work with X11 only, such as the EWMH/NETWM spec and Xsettings spec. To port to Wayland, these problems need to be solved first. Gnome and KDE guys will fix them so we can just wait. Then why Qt 5.1? Because Qt 5.1 added back the once-removed X11-related APIs. So porting from Qt 4 to Qt 5.1 should be the most smooth path. It takes time for distros to adopt Qt 5.1, though.

Please use PCManFM-Qt git version for now.

As many people know, a Qt port of PCManFM is under heavy development. Although we released PCManFM-Qt 0.1 previously, it contains some bugs and memory leaks. Most of the issues are already solved in the latest source code in our online git repository and will be available in the next release. However, the new code depends on the latest libfm 1.2, which is not released yet. Due to the small delay of libfm release, the new release for PCManFM-Qt cannot be made at the moment. Brave users who cannot wait for the final release are encouraged to try the latest git version of libfm and PCManFM-Qt to get the latest features and fixes.

Here is a short list of what’s in the latest git version (and will be in the next release):

  1. Fix several important memory leaks in version 0.1
  2. Some optimizations for memory usage and speed are done
  3. Full thumbnail support (can show thumbnails for image files and other formats with external thumbnailer installed)
  4. Extract thumbnails from EXIF data of jpeg files (via libfm 1.2)
  5. Optimize column widths of detailed list view automatically
  6. Correctly handle desktop icons when a work area is set
  7. Detects icon theme automatically according to current desktop environment. No need to set an icon theme manually in LXDE, XFCE, Gnome, and Razor-Qt.
  8. Some other small bug fixse

The current code of PCManFM-Qt in the git repo is nearly ready for daily use. The memory usage and overall performance are acceptable, too. When Andriy finishes libfm 1.2 and makes a new release, I’ll make one for PCManFM-Qt at the same time. Before that, users are encouraged to try the git version.


> git clone git://

For compiling the latest code in git, you also need the git version of libfm and menu-cache:
> git clone git://
> git clone git://

Have fun!

A Guide for Migrating from Gtk+ to Qt

Since I started learning Qt recently, I noted some issues when trying to port Gtk+ programs to Qt. There are tons of tutorials for Gtk+ and Qt, but a guide for porting is lacking. Most of the articles comparing Gtk+ and Qt did not go into detailed issues people will encounter during coding.
To help people porting their Gtk+ programs to Qt, I just started a wiki page documenting what I’ve learned so far.
Currently it provides a long table listing equivalent Qt classes for
commonly used GtkWidget classes. Since I cannot find a similar list with Google, I built one. This is useless for experts, but it’s very handy and helpful for Qt beginners who already know Gtk+. The mapping between Gtk+ and Qt classes is not yet finished, but I’ll try to make it complete soon.
I also documented things you need to know to safely mix glib/gio/GObject code with Qt. Later I’ll add docs describing how the translation systems differ.
I hope that developers interested in this topic can help edit the wiki
page to make it more complete and free from errors. It’s still a work in progress but I hope it helps someone as more and more people are using Qt and some more LXDE components *might* get Qt ports later. BTW, since Ubuntu guys is moving toward Qt, this also helps them.

PCManFM Qt 0.1.0 released

Hello world,
I just released PCManFM Qt file manager 0.1.0, the first Qt port of PCManFM.
The tarball is available for download from our project page.
You’ll need libfm to build it (which is included in many distros).
P.S. When running the program for the first time, please choose an icon theme from the [Edit] / [Preferences] menu. Otherwise you’ll get no file icons.
If you install the program into /usr/local, don’t forget to run “ldconfig” after installation, or libfm-qt won’t be correctly loaded by the loader.
This release contains no thumbnail support yet.
However a fully working thumbnail support is already in the git.
Because this requires some changes to the upstream libfm library,
it’s scheduled for the next release and not make public at the moment.
To turn on the desktop icon management feature, run with the command:
> pcmanfm-qt –desktop
Generally it’s a good idea to add this command to your session startup script.
To turn the desktop icon manager off again, do this:
> pcmanfm-qt –desktop-off
If you don’t want to use the desktop icons, you can still add the
command to your session startup script:
> pcmanfm-qt –daemon
In this way, it will becomes a background daemon. Every time you need
to open a folder with pcmanfm-qt, it can be shown “immediately”.
BTW, please don’t mail me and ask if PCManFM will shift to Qt.
The Gtk+ and Qt versions will coexist.
There will still be new releases for the Gtk+ version in the future.
The Qt port is only an alternative, not a replacement.
Thank you!
I, however, need to admit that working with Qt/C++ is much more pleasant and productive than messing with C/GObject/GTK+.
Since GTK+ 3 breaks backward compatibility a lot and it becomes more memory hungry and slower, I don’t see much advantage of GTK+ now. GTK+ 2 is lighter, but it’s no longer true for GTK+ 3. Ironically, fixing all of the broken compatibility is even harder than porting to Qt in some cases (PCManFM IMO is one of them).
So If someone is starting a whole new project and is thinking about what GUI toolkit to use, personally I might recommend Qt if you’re not targeting Gnome 3.
Update 2013-03-27:
I got some feedback about the toolkit choice above. Don’t get me wrong. I’m not saying that gtk+ is bad and did not intend to start a toolkit flame war. If you’re going to use python, C#, or other scripting language, gtk+ is still a good choice due to its mature language bindings.
Vala  is attractive initially, but after trying it in real development, you’ll see the shortcomings of this approach. Because it sometimes generates incorrect C code that still compiles, we got some really hard-to-find bugs. So we need to examine the generated C code to make sure it does things right. This takes much more time than just writing plain C code myself. Besides, the generated C code is not quite human-readable and debugging becomes a problem. Another issue that’ll hit you is the problems in the library bindings. Though there exists many vala bindings for various C library, their quality is uncertain. Finally, debugging, examing, and fixing the bindings all the time takes even more time and offsets the time saved by using Vala.
To sum up, for compiled binary programs, Qt IMHO is a good choice to consider if you don’t hate C++.

PCManFM Qt port is 85% finished now!

A picture is worth a thousands words so again let’s see the screenshot first.

PCManFM Qt with desktop manager turned on

This is the Qt port of PCManFM with desktop management feature turned on. The desktop icons and the wallpaper were painted by PCManFM-Qt, just like the gtk+ version of the original PCManFM. The new Qt port is in a pretty good shape now.
Although it’s not yet ready for production use, it’s almost there. About 85% of the planned features are finished.

What already works:
  1. Nearly all folder browsing features
  2. Change icon theme
  3. Preferences dialog (most options work)
  4. Load/save settings
  5. Single instance + dbus service
  6. Command line options
  7. Desktop icon manager: enable with “pcmanfm-qt –desktop”. You can add “pcmanfm-qt –desktop” to the startup script of your desktop environment/window manager.
  8. Change wallpapers via “Desktop Preferences” dialog
  9. Mount remote filesystems and removable devices (requires gvfs)
  10. Split into pcmanfm-qt and libfm-qt library.
  11. Install libfm-qt header files to /usr/includ/libfm-qt along with a pkgconfig file, so later libfm-qt can be used in other Qt programs
  12. Most file operations, move/copy/symlink/trash/rename, change file attributes in the file properties dialog.
  13. Basic drag and drop support (very basic)

Things which do not work or are still work in progress:

  1. Create new folders/files
  2. Edit bookmarks
  3. Auto-mount/auto-run for removable devices
  4. No thumbnail support yet. (This may require some changes of the upstream libfm library)
  5. No ABI version (libtool soname not set yet)
  6. No translations yet (Qt Linguist and the *.ts files are hard to work with and lack features I need, I consider using GNU gettext instead)
Also noted that the git repository is now moved to:
The original libfm-qt repo will be removed later.
The binary program pcmanfm-qt and the library are bundled in the same package.
Please help test and give some comments.
If anyone is interested in helping the development, patches are welcomed.
Thank you!

PCManFM file manager is ported to Qt?

No, LXDE will NOT use Qt. Don’t panic!!
It’s just one of my side projects and was an experiment to test how good libfm and Qt are. Since the core library of PCManFM, libfm, is carefully separated from its Gtk+ UI code, theoratically it can be ported to other GUI toolkits. To give it  a test, I played with Qt recently. The result is quite satisfactory and impressive. I must admit that working with Qt is quite pleasant.

Everybody loves screenshots so here is one.

At first glance, this looks like the original GTK+ version very much. Because I choose “Cleanlook” Qt style, it highly resembles Gtk+ “Clearlooks” theme. Besides, I load the “elementary” icon theme. Though it matches the looks and feels of typical Gnome/Gtk+ programs, this is an 100% pure Qt program.

The most interesting and unique part of the PCManFM Qt port are:

  1. No KDE dependency. Really, it’s a lightweight pure Qt4 program.
  2. Almost as fast as the original Gtk+ version. I have not taken any time to do optimization yet. It’s possible to make it faster after optimization.
  3. Uses Libfm + glib/gio, and supports gvfs. So you can mount remote filesystems.
  4. Source code is clean and short, written in C++.
  5. Desktop independent, do not depend on any specific desktop environment (although it uses glib/gio/gvfs, it does not require Gnome)
  6. Built with cmake. No more autotools.
  7. Later, when the APIs becomes stable, I’ll make it two parts, PCManFM main binary and libfm-Qt, which can be used in other pure Qt programs.

For decades, people from the Gnome/Gtk+ camp and the KDE/Qt camp don’t work each other sometimes. Each of them likes to reinvent the wheel and create functionally equivalent programs with different toolkits. The fact is, technology from both camps can be mixed very well. Qt-based UI sit on top of low level platform APIs from Gnome stack is another good option.

PCManFM Qt, when finished, will be a perfect mix of Gnome libraries + Qt-based UI.  I think it’s a good news for who like Qt but don’t want to install KDE.

The source code is available here:
git clone git://

It’s still a work in progress and many parts don’t work yet.
If you’re a Qt developer and is interested in helping the development, feel free to contact me.

P.S. Special thanks to KDE developers Aaron Seigo and Will Stephenson. I met them last year during an open source event “COSCUP 2012” in Taipei, Taiwan. They gave some instructions about how to use Qt. Then, I finished the basic skeleton of this port at that night.

Call for review: PCManFM is almost ready for a new release

I’m here to call for a review for PCManFM as the source code in git isin quite good shape now.Many known bugs are fixed and I did much refactor to the tabbedbrowsing part and merge changes in tab-rework3 branch with master.Please help test and update translations in various distros. If things are ok, I propose a new release.

Some major changes:

  1. “Reload Folder” is available now in View menu.
  2. “Directory Tree” mode is available in side pane.
  3. Filesystem size is updated in a more correctly and efficient way.
  4. Many bugs causing crashes are fixed.
  5. Shows a warning icon in toolbar when running as “root”.
  6. Supports menu keys.

Minor changes:

  1. Fixed some memory leaks.
  2. ~ and / to move focus to location bar
  3. Improve internal structure of PCManFM.
  4. Code cleanup.

A new release as 0.9.9 is required. Please help review and test the code in git.Thanks a lot!