Mint MATE Monitor Brightness

I ran into a rare but not unheard of problem this morning while working on my desktop computer (running Linux Mint with the MATE desktop, and using a Dell monitor). Due to a somewhat funky arrangement of solar position, clouds, and possibly other celestial entities, the natural light behind my monitor caused a glare that made my eyes hurt a bit and caused me to have trouble seeing the screen. (Some what I guess you might call after-images were messing with my vision.) To reduce the glare, I wanted to dial down the monitor brightness ... but could not figure out how. The buttons on the Dell monitor are unlabeled, and I was not overly excited about a bunch of trial-and-error button pushing. So I naturally went to the system's display controls ... which did not have a brightness setting.

When I had some free time, I started searching the web for how to adjust display brightness in MATE, where to find GUI tools or applets for display brightness, and so on. I found lots of seeming helpful posts that either (a) referred to controls that do not exist in my operating system, despite allegedly being specific to MATE and possibly to MATE on Linux Mint or (b) pointed me to an applet that did not work (in some cases possibly because it only works on laptops for some reason?).

So, bottom line, I eventually wrote a bash script with a primitive GUI to let me futz with the display brightness. It uses the xrandr  and zenity commands, either or both of which may need to be installed. (You can run "which xrandr" and "which zenity" in a terminal to see if you have them.) Once you have them, run "xrandr" in a terminal with no options to find out the name of your display (DP-2 in my case). Substitute that for DP-2 in the following script (and remember to make it executable with "chmod +x <your script>.sh", and you should be in business.

#!/bin/bash

# Adjust display brightness (1.0 being the default brightness).
# You can get the monitor name (DP-2 here) by running 'xrandr' in a terminal.

target=$(zenity --entry \
                --title="Set Display Brightness" \
                --text="Set a brightness level (base value = 1.0):" \
                --entry-text="1.0")
xrandr --output DP-2 --brightness $target
zenity --info --text="Click OK to close the terminal."

MATE Misadventure

My desktop computer runs Linux Mint with the MATE desktop environment. I know Cinnamon is fancier / trendier, but I'm used to MATE, plus I run it on my "vintage" laptop (which in the past struggled to run Cinnamon) and it's nice to have the same environment both places.

Until recently, the only issue I had with MATE was an occasional glitch in the panel. I "solved" that by creating a script to reset the panel, which I invoke manually as needed. Of late, though, I have run into a new problem. It may or may not be related to a recent operating system upgrade, which forced my rather long in the tooth PC from the 4.x kernel series to the 6.x kernel series.

Normally, when I power up my PC it opens a few applications (including Thunderbird and Firefox) in the foreground as well as the usual cornucopia of things in the background. That still happens most days, but every so often something goes splat. The desktop appears, complete with icons, but the MATE panel does not. More importantly, none of the application windows are visible (although, somewhat weirdly, notifications of incoming messages from Thunderbird will pop up, even though Thunderbird itself is invisible). So everything appears to be running, but nothing beyond the desktop (and those popups) is displaying.

I still have no explanation of why this happens, but I now have a workaround. It turns out that marco is the window manager in MATE. The first step (on a day when things were working) was to open a terminal, run pgrep marco followed by ps -l XXXX (where XXXX was the PID of the marco process), and take note of the command line options (in my case, "--composite --replace"). Next, I created a bash script containing the following:

pkill marco
marco --composite --replace &
disown

This kills the marco process that is acting up and starts a new one. As I discovered today, without the first line the script still works but leaves the original marco process in memory as an orphan. I bound the script to an unused key combination (using the "Keyboard Shortcuts" application in the Mint menu). So now if MATE screws up after booting, I just type the key combination and things are instantly fixed.

Restarting the MATE Panel

I know that Cinnamon is the trendy choice for desktop environment with Linux Mint,  but ever since an unfortunate misadventure with video drivers I have been using the somewhat more stable and somewhat faster MATE (pronounced Ma-Tay, per their home page) environment. Overall I am very happy with it. There are, however, occasional hiccups with the panel, the bar along one edge of the display (bottom in my case) containing launchers, tabs for open applications and general what-not. Occasionally, for reasons beyond me ken, some of the icons will be screwed up, duplicated, or duplicated and screwed-up. This morning, for instance, I found not one but three iterations of the audio output icon (looks like a loud speaker, used to set audio preferences). The first icon had the normal appearance, meaning audio was enabled, while the second and third were indicating that audio was muted. (Despite the 2-1 vote against, audio was in fact enabled.)

Glitches like that do not render the system unusable, but they are annoying. So I dug around a bit and discovered that the system command mate-panel. Run from a shell script or a launcher, the command mate-panel --replace seems to do the trick of restarting the panel (and hopefully fixing the glitch that made you restart it).  If you run the command from a terminal, be sure to push it to the background using an ampersand (mate-panel --replace &). Otherwise, it will tie up the terminal session, and when you break out of it (probably via Ctrl-C) the panel will rather unhelpfully evaporate.

Mapping Trackball Buttons

For years, I've used a Logitech M570 wireless trackball with my Linux Mint PC. I generally prefer trackballs to mice -- no need to lift and reposition after a bunch of movement -- and I find that using my thumb, rather than my index finger (or, if I'm in a bad mood, my middle finger) to move the cursor is less fatiguing for my hand and wrist. The M570 works fine with Linux (at least Mint and Ubuntu) with no need for additional drivers.

In addition to the usual (at least for non-Mac users) three main buttons (left, write and combination scroll wheel/third button), the M570 has a couple of secondary buttons, which Logitech describes as "large, easy-to-reach Back/Forward buttons". I'm not sure I'd agree about "large", but I agree that they are easy to reach, and up until my most recent operating system upgrade I would have agreed they acted as back and forward buttons. Prior to the upgrade (and with no special configuration on my part, at least that I can remember), the extra buttons acted like page up and page down in every web browser or document reader that I used. After the upgrade (and switch from the Cinnamon desktop to the Mate desktop), their behavior changed. In the Firefox web browser, they would switch among tabs rather than vertically scrolling the current tab. In Xreader and Acrobat Reader, they also did not move forward backward among pages. (I don't recall trying to read multiple documents at once to see if they would switch among open documents.)

I find the forward/backward action rather handy with multipage documents and long web pages, so I wanted the previous behavior back. It turned out (after some research) not to be hard to do.

The first step is to install the xbindkeys and xautomation packages, both available from the Canonical repositories. This can be done via Synaptic or by running

     sudo apt-get install xbindkeys
     sudo apt-get install xautomation

in a terminal. (I also installed xbindkeys-config, which xbindkeys "suggests", but I don't think it's really necessary.) The xautomation package provides a command xte that can fake a key press.

The second step is to determine what button numbers are assigned to the forward and backward buttons. Run

     xev | grep -i button

in a terminal. This will open a small window with a target. Position the cursor over that window and click each of the buttons. You will see two messages in the terminal for each button, one for the press and one for the release. Look for the button numbers. For me, they were button 8 for forward and button 9 for backward, but your mileage may vary.

The third step is to configure xbindkeys to translate the extra trackball buttons appropriately. The configuration for xbindkeys is kept in a plain text file named .xbindkeysrc in your home directory (~/.xbindkeysrc). You can either create a new one (if you don't have one yet, or if there is nothing in it you want to keep) containing the lines below, or append those lines to the existing file, using your choice of text editor.

# Key bindings for Logitech M570 trackball
"xte 'key Page_Up'"
b:9
"xte 'key Page_Down'"
b:8

If your button numbers differ from mine (8 and 9), edit the lines accordingly. Note carefully the single and double quotation marks; xte seems a bit finicky about them.

Finally, you'll want to test this. You need to restart xbindkeys to get it to read the modified configuration file. Theoretically you can do this by running

     killall -HUP xbindkeys

in a terminal, but I found it necessary to restart the X server (after closing any applications using it, such as my web browser and email client). Typically Control+Alt+Backspace will do the trick. After that, try the trackball keys and hopefully they'll behave as expected.

Mint Upgrade Woes

As I mentioned a couple of months ago, I upgraded a laptop from Linux Mint 17.3 ("Rebecca") to 18.0 ("Sarah") with minimal difficulties. My laptop serves as a guinea pig for these things. Once I'm sure things work fine on the laptop, I'll consider upgrading my desktop as well.

A few days ago I finally undertook the desktop upgrade. By this time the current Mint version was 18.1 ("Serena"). I was expecting a smooth ride, because I forgot one key difference between laptop and desktop: the desktop has an NVIDIA display card. I can't believe I forgot to take that into account, because I've written before about problems with NVIDIA hardware drivers.

Shortening (somewhat) a long and painful story, the initial upgrade left the system with an unusable display, forcing me to do a fresh install of 18.1 from CD (which, among other things, removed a whole lot of packages that will need to be reinstalled). Even after that, the display was an adventure.

The initial installation gave me a choice between the open-source Nouveau driver and version 304.132 of the NVIDIA "legacy" driver. This is the same version that previously caused major headaches. Last time it cause a black screen. This time, presumably due to updates in some system modules, I actually got the background for my desktop (with the Mint logo) and ... something. At first it showed only the upper left corner of my desktop, but after assorted uninstall/reinstall/desperately-try-something machinations, I got to the point where it showed the entire desktop ... except the start button and bottom panel. Oh, and windows did not have the maximize/minimize/close controls, some windows could be dragged while others could not, I don't think I could resize windows, and for some reason the menu button in Firefox didn't work. Other than that, things were peachy. I tried using the sgfxi script to change driver versions, but there was no joy to be had. Of the subset of listed versions that I tried (there were too many to mess with every one), the older ones were allegedly incompatible with one of the libraries (Xorg, I think) and the newer ones had the same problems (or were incompatible).

So I decided to stick with the Nouveau drivers, which install with Mint and are the default choice. Their behavior was also a bit odd. Depending on where I was coming from (fresh install, switching from NVIDIA to Nouveau, something else), they might recognize my 1920x1080 Samsung monitor correctly or they might think that my only monitor was a laptop display (limited to 640x480 resolution). The latter resulted in a butt-ugly and more or less unusable result. Eventually I got Nouveau working at 1920x1080 and thought I was good to go. In fact, I almost was.

The one deal-breaker with Nouveau came when I clicked links in email messages (using Thunderbird) to open them in the Firefox browser. Seemingly randomly, about 3/4 or so would work, but occasionally one would lock the system solid (no response to keyboard or mouse) with a corrupted display ("white blizzard"). The only recourse was power off/power on. Google searches suggested changing a couple of settings in Firefox regarding hardware acceleration. One setting no longer exists; I toggled the other, but it did no good.

I put up with that for a day or so before deciding that, absent any cure, I would have to find a way to use the NVIDIA driver. It occurred to me that the things it was screwing up (window controls, desktop panel, menu button ...) were things under the purview of the window manager (which was Cinnamon). So I installed MATE alongside Cinnamon and switched to it. Sure enough, I got back the main menu and bottom panel, window controls and so forth. It's been stable for a few days now (with no freezes from clicking links in email messages), so I think I've confirmed my thesis that the legacy NVIDIA driver does not get along with Cinnamon, at least on my machine.

Bottom line: anyone who's getting screen freezes using an NVIDIA driver with Mint and Cinnamon might want to consider trying an alternate desktop environment.

A Panel Launcher Menu for MATE

A recent upgrade to my Linux Mint PC forced me to switch the desktop environment from Cinnamon (which I've been using for years) to MATE. For the most part, that was painless, but a few things from my old desktop did not translate well.

I had the icons on my Cinnamon desktop organized in a way that made sense to me (but would baffle anyone else); MATE decided they needed to be alphabetized and snapped to a grid. That will be easy (but tedious) to fix. The trickier part was recreating the mix of indicators and applets I wanted in the panel at the bottom of the screen.

One feature I've gotten used to is having an applet that pops open a customize menu of launchers. There's a really excellent Gnome shell extension named MyLauncher that is easy to add in Cinnamon but apparently not available for MATE. Clicking the MyLauncher panel icon opens a pop-up menu that is fully customizable. Menu entries are text, not icons, and you select what the text says and what it does. As one example, I have an entry reading "Search files" that launches Searchmonkey (which I heartily recommend).

I'm a bit finicky (anal?) about how such a menu should work.

1. I want it to list just selected applications, not every application on the system.
2. I want text prompts, not icons. (If I'm thinking "search for a file", my brain is not translating that to "look for a picture of a monkey".)
3. I want to choose the prompts myself. (Before the morning coffee sinks in, I may not remember that "searchmonkey" is the command I'm looking for.)
4. I want a single list; I don't want to have to wade through categories (as one does in the main Mint menu).
5. Adding/editing the menu needs to be reasonably easy.

MyLauncher met all those criteria. After the switch to MATE (and after discovering I could not use MyLauncher any more), I went looking for something equivalent but struggled to find an adequate substitute. It is easy to add an instance of "Main Menu", "Menu Bar" or "mintMenu" to the panel, but all of those default to listing every application (violating item 1 above) and use the same categories as the main menu (violating item 4). I think I could edit my way past that, but deleting a zillion applications added by default is more work than manually adding the handful I want. Also, when a new application is installed, it is added to the main menu automatically, and I'm not sure if it would wind up added to my custom menu as well (forcing me to edit out each newly installed application).

Anyway, after a bit of searching I found a solution with which I'm comfortable. It combines two programs. Rofi is something of a Swiss army knife, with many functions, one of which is providing menus (with search-as-you-type functionality). Rofi is available from the Canonical repositories, so I was able to install it using Synaptic. The program that actually produces the menus is Menugen, which is actually a set of BASH scripts. There's not much to installation: you just download it, unzip it and store it someplace.

With Rofi and Menugen installed, I just had to load my old MyLauncher menu into a text editor, massage it into the format Menugen wants, and park it someplace. I made the new menu an executable script that calls menugen to interpret it. I then added to the panel a custom launcher invoking my menu script, and that was that.

In case it helps anyone, here's an abbreviated version of my script:

#!/home/paul/Software/menugen-master/menugen
#begin main
name="Quick Launch"
numbered=false
add_exec "Freeguide"  'freeguide'
add_exec "Text editor"  "xed"
add_nop "-----------------"
add_exec "Synaptic"  "gksudo synaptic"
add_nop "-----------------"
add_exec "Terminal"  "terminator"
#end main

The add_nop commands add "no-op" lines (separators), while the add_exec commands add menu entries. There is also an add_item command for adding menu entries and an add_link command for linking to a submenu. The primary difference between add_item and add_exec (at least as far as I'm concerned) is that add_item returns you to the menu after you make a choice and add_exec closes the menu after you make a choice (which is the behavior I want).