mirror of https://github.com/MidnightCommander/mc
110 lines
5.2 KiB
Plaintext
110 lines
5.2 KiB
Plaintext
Solving keyboard related problems
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with XTERM
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and GNU Midnight Commander
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(and other programs as well).
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Xterm brings a handful of problems with input keys and their translations.
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Some of these problems include xterm's failure to make a difference between
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shifted and not shifted function keys (many keyboards do not have more than
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10 or 12 function keys, so it is useful to generate higher function keys (11
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- 20) by pressing Shift and function key - 10 (e.g. Shift+F3 is F13). Xterm
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also doesn't send Alt+character and Meta+character as something other than
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plain character. Also, home key does not work on most systems. And keypad
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operator characters (+, -, /, *) send different sequences than normal +, -,
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/, * (or sometimes do not send anything).
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Please note that if you want to use the Alt key on an XTerm, you have to
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make sure you use:
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XTerm*eightBitInput: false
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Otherwise, you will just get accented keys.
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Fortunately this can be solved, since xterm is written on top of the
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X Toolkit Intrinsics, which has a built-in feature of event translation
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tables that can be specified using X resources. This doesn't apply to rxvt,
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where the only solution to this problem would be patching rxvt's sources and
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recompiling. So from now on, we are speaking only about xterm (and its
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modifications, like color_xterm and ansi_xterm).
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Xterm brings two new Xt widgets (if you don't know what they are it doesn't
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matter), vt100 and tek4014 (these are used for the terminal display in vt100
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and tektronics mode). The translation table is specified in
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*vt100.translations and *tek4014.translations resources.
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You can see a sample in xterm.ad file in this directory.
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If you want to install these translations, bear in mind that you have to
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keep your terminfo and termcap in sync with these. So if you install
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xterm.ad, you have to install xterm.ti and xterm.tcap (or do necessary
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changes yourself).
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xterm.ad has to be loaded into the Xrm (X resource manager), either by xterm
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itself or by xrdb utility. There are many places you may want to install it
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to; the decision is yours. Preferably it should go to your personal
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$HOME/.Xdefaults file (if you have any). This file is automatically loaded
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using xrdb whenever you start the X server (it is done by startx and openwin
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scripts). Another possibility is to put this into
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$X11ROOT/lib/X11/app-defaults/XTerm or wherever your app-defaults file of
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xterm is and whatever is its name (sometimes it will have to be XTerm-ansi,
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XTerm-color etc.) Or you can put this anywhere and call
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xrdb xterm.ad
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from any script you run on X11 startup.
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xterm.ti (terminfo database source) is installed by running `tic xterm.ti'.
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tic will compile it and place it into your TERMINFO directory.
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xterm.tcap is the xterm (and xterm-color) termcap entry. It is based on the
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newest termcap database from http://www.ccil.org/~esr/ncurses.html, but
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contains a bunch of changes to make all the above mentioned keys work. Even
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if mc is compiled so that it uses terminfo, you need to install the termcap
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entry so that other programs which use termcap will behave correctly. You
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have to edit your /etc/termcap and replace xterm and xterm-color entries
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with those from xterm.tcap.
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The xterm.ad translation table contains many items (some of them may be
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unnecessary) but are included only to make it work on all different xterms
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(xterm terminfo and termcap databases have different sequences for the same
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keys in every different database, so xterm.ad works as a stardard to make
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xterm.ti and termcap happy). If you find that xterm works well even if you
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delete some lines from the translations, feel free to do it.
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By default, Alt+character keys received by mc are generated in xterm.ad by
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Alt modifier plus the key. On some systems, you may want to change this to
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the Meta modifier (e.g. if the Alt modifier is missing). You do it by
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replacing a letter s at the beginning of table lines with letter m.
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And what you might want to know, if you are going to change anything, is:
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Each line looks like
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modifiers<Key>keyname: string("something") \n\
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where modifiers can be:
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a for alt
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m for meta
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c for control
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button1 (2, 3) for mouse buttons.
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The string is generated whenever the named key is pressed while the
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modifiers are in a state matching the specification. Naming a modifier
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specifies that the modifier must be pressed. A ~ in front of a modifier
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name specifies that the modifier must NOT be pressed. If the set of
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modifiers is preceded by !, unmentioned modifiers must not be
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pressed; otherwise their state is ignored.
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After <Key> you specify a name of the key (if you don't know a canonical
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name of any key, see $X11ROOT/include/X11/keysymdef.h (keynames are the
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names there without leading XK_). Then there can be any sequence of string
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statements which send the string to the tty line, as if the user typed that
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sequence of characters. If it has the form string(0xXX), where X's are
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hexadecimal digits, then the ascii character of that value is sent rather
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than 0xXX.
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This is a subset of all the translation table features. If you want a
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complete reference, see xterm(1) and X Toolkit Intrinsics manual Appendix B.
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Please, if you find any problems or errors in this stuff, let me know by
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e-mail to
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mc-devel@gnome.org.
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