Hack

I decided I needed a clock in my living room, and remembered I had this Matrix Orbital VFD2041 vacuum fluorescent display in my junk box, so I whipped up a few lines of C code to make it show the current time. The VFD connects to my home theater PC via its RS-232 interface and a USB RS-232 dongle.

Here's the source:

• vfdclock.tar.gz

I decided to try using GNOME Terminal with ugly fonts — that is, bitmap fonts which are not anti-aliased. The goal of this experiment was to improve terminal performance when scrolling large amounts of information in a big window. At the end of the day, the performance was not improved in my case. (I have my monitor rotated 90° for a portrait display, and I think my use of rotation may be a bottleneck for my graphics throughput.) However, I decided to keep the ugly fonts anyway, since it seems to allow me to use smaller fonts without sacrificing legibility.

Since there were a few steps involved in forcing the terminal to use ugly fonts, without allowing the ugliness to spread to other applications, I decided to document my findings here.

Finding ugly fonts to use

Some modern systems may not ship with fonts which are sufficiently ugly. Hongli Lai has written about this on his blog, and provides the MiscFixed font for download. I downloaded and installed this font.

Configuring Fontconfig to allow ugly fonts

Surprisingly, the MiscFixed font is not available in GNOME Terminal's font selection dialog box, even after I installed it! It turns out that modern systems (or at least my Ubuntu 8.04), in a noble effort to protect delicate users from the shock of seeing ugly fonts at any cost, have actually configured Fontconfig (the system font manager) to reject bitmap fonts.

Fontconfig can be reconfigured to allow bitmap fonts, for those of us who aren't afraid of cutting ourselves on the sharp edges of these harshly defined glyphs. Most of the Fontconfig configuration is in the form of symbolic links to XML fragments in the /etc/fonts/conf.d directory. I found the link which disallows bitmap fonts (70-no-bitmaps.conf on my system) and replaced it with a link which permits these fonts (../conf.avail/70-yes-bitmaps.conf on my system). Lo and behold, the ugly MiscFixed font appeared in the terminal's font selection dialog box for my enjoyment!

Unfortunately, my elation was short-lived. Other applications inexplicably starting preferring ugly fonts over the beautiful anti-aliased TrueType fonts they previously used. In particular, my web browser began to render most web pages with fonts which were not just ugly, but bitmap-scaled into horrifying contortions. After my eyes stopped bleeding and I completed several rounds of post-trauma counseling, I decided I needed a way to have a special configuration of Fontconfig just for the terminal.

Using an alternate Fontconfig configuration

First, I set up an alternate copy of the Fontconfig configuration by copying /etc/fonts/fonts.conf to fonts-bitmap.conf. I also made a copy of the /etc/fonts/conf.d subdirectory as conf-bitmap.d, configured it to allow bitmap fonts, and changed the new fonts-bitmap.conf to use it.

According to the Fontconfig documentation, I should be able to run applications with the FC_CONFIG_FILE environment variable set to the new configuration file, and have them use the alternate configuration. This didn't work for me — GNOME Terminal used the system configuration regardless. Perhaps my system is too old, or too new, or maybe Pango's use of Fontconfig interferes.

In my quixotic quest for ugly fonts, I wrote a small wrapper library which, when preloaded into an application with LD_PRELOAD, will intercept calls to open(). Requests to open the fonts.conf file will be remapped to open the fonts-bitmap.conf file instead. For convenience, I configured a launcher icon in the GNOME Panel to run the terminal with my wrapper library using the following command line:

sh -c "LD_PRELOAD=~/work/fc-config-override/fc-config-override.so exec gnome-terminal"

Using this method, I can now use ugly fonts in the terminal, while using attractive fonts in all other applications. A link to the wrapper library is below.

Download:

• fc-config-override.tar.gz

The presence of multiple "clipboard" selection buffers in the X Window System has long been a source of irritation with me, and I frequently end up pasting the wrong thing. A few years ago, I hacked the xterm terminal emulator program to always copy into both buffers, and this solved the problem for me. However, I've been playing around with GNOME Terminal lately, so I recently patched its source code to do something similar.

Background

The root of the problem is that there are two different "selection buffers" that are commonly used in the X Window System:

CLIPBOARD

The "CLIPBOARD" selection buffer is used for the cut-and-paste functions that most users are familiar with: Selecting the "cut", "copy" or "paste" menu items from the application's "Edit" menu, or using the corresponding CTRL-X, CTRL-C, or CTRL-V shortcut keys. This selection buffer is the standard means of performing cut-and-paste operations in most modern applications. However, this selection buffer is unfortunately not used when you merely highlight some text in the GNOME Terminal.

PRIMARY

The "PRIMARY" selection buffer receives data when the user highlights text with the mouse. The text in this buffer is pasted when the user presses the middle mouse button in an application's text entry field. This cut-and-paste buffer is a legacy function which new users are generally not told about, in the interests of avoiding mass confusion. Most modern applications support this buffer.

The annoyance is that text highlighted in GNOME Terminal (and thus stored in PRIMARY) can be pasted into another application by clicking the middle mouse button, but cannot be pasted with CTRL-V. Likewise, text copied from the terminal with SHIFT-CTRL-C (or Edit->Copy) might not be available for pasting with the middle mouse button. I frequently get into situations where I have one bit of text in PRIMARY, and another in CLIPBOARD, and I inevitably use the wrong paste function.

A patch for GNOME Terminal 2.22.3

The attached patch modifies the terminal source code to always copy selected text into CLIPBOARD shortly after it has been copied into PRIMARY. Thus, when you highlight a bit of text in the terminal, it can be pasted into another application with either the middle mouse button or CTRL-V.

This patch is for the GNOME Terminal 2.22.3 source code. I'm sure the patch won't work on more recent versions because they've rearranged a few things, but the basic concept should still work. The patch for xterm I wrote a few years ago is also still available.

• gnome-terminal-2.22.3-friendlyclipboard.patch