draw() runs over all lines of the screen and renders only the dirty lines,
this avoids render lines which are not modified since last draw() call. In
this moment the main loop is something like:

     - Wait something to read from file descriptors
     - Read from pseudo tty
     - Call draw() for rending
     - Read X events

This cause the problem that all the X events that have to update the screen
have to call draw() (because draw() is called before of X events handling),
so you can have multiples renderings in only one iteration, that will waste
a lot of resources.

This patch change the main loop to:

     - Wait something to read from file descriptors
     - Read from pseudo tty
     - Read X events
     - Call draw() for rending

So X events don't have to worry about rendering, because draw() is called
after them.

The only place where draw is called outside of the main loop is in redraw(),
but it is necessary for getting a good tput flash.
---
 st.c |   29 ++++++-----------------------
 1 file changed, 6 insertions(+), 23 deletions(-)

The main loop waits until there is some data to read in file descriptors of
the X server or the pseudo tty. But it uses a timeout in select(), which
causes that st awake each 20 ms, even it doesn't have something to do. This
patch removes this problem removing the timeout, which is not needed.
---
 TODO |    1 -
 st.c |   27 +++------------------------
 2 files changed, 3 insertions(+), 25 deletions(-)

It is necessary call to XSync if you want a good tput flash, because in
other way you can not be sure that white screen will be shown.
---
 st.c |    1 +
 1 file changed, 1 insertion(+)

XdbeQueryExtension() tells to the caller if the Xdbe extension is present in
the X server, so it should be called for sanity. But like is said in
XdbeQueryExtension(3):

	No other Xdbe functions may be called before this function.  If a
	client violates this rule, the effects of all subsequent Xdbe calls
	that it makes are undefined.

it is mandatory call this function.
---
 st.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Roberto Vargas.

By default text files are line buffered, and this means that -f option will
not write the line until a \n is printed. This is not very useful for
debugging, so a call to fflush was added. This patch substitute this call
(which will be done by each character painted) by the full remove of the
buffering in the file.
---
 st.c |   12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

If malloc  or realloc fail they return NULL. Theorically this condition
should be tested in the code, but it's a strange condition today (basically
if this is hapenning thenyou have a big problem), and even Linux never returns
NULL in the default configuration (only if the process don't have room in
the space address, something a bit impossible in the case of st). But stis
enough small for being executed in low resources computers where this can be
a real problem. So the easy way is creating a wrappers function for them and
call to die in case of error.
---
 st.c |   44 +++++++++++++++++++++++++++++++-------------
 1 file changed, 31 insertions(+), 13 deletions(-)

st marks the active selection using reverse colors in the box selection, but
once that another window becomes owner of the selection, it is very
confusing that st keeps highlight the old selection. Usually terminal
emulators remove the highlight when it is not valid anymore.

X sends a SelectionClear event in this situation, so we only have to add a
callback which unhighlight the selectin box.
---
 st.c |    9 +++++++++
 1 file changed, 9 insertions(+)

Some programs use the alternative screen (vi, less, ...), whose
content is different of the main screen. If you select text in one of
the screen, you don't wait the box selection is painted in the other
screen, so it is necessary check if the selection was done in the same
screen we are going to paint. Before to this commit, you could do
something like:

	$ LESS="" ls | less
	(select some code)
	q

and selection box remains drawing in the main screen, but the content
of selection keeps text of the alternate screen.
---
 st.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

---
 st.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

When it is called DECSCNM all lines become dirty, because it is necessary
redraw all lines for getting the new colors. It is easy see the problem
running 'echo ^[[?5h'.

In order to get a correct flash when running tput flash is necessary wait
after DECSCNM, until the changes are displayed, because in other case the
switch between reverse on/reverse off will be too much fast and nothing will
happen.
---
 st.c |   12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

This is a theorical feature listed in http://st.suckless.org/goals. All the
input/output of the terminal will be written to a file, which can be very
useful for debugging, and also allow interconnect st to other process
through named pipes.
---
 st.1 |    6 ++++++
 st.c |   14 +++++++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

SM and RM can receive multiple parameters, but the code only was accepting
only one. This patch join the code of set and reset modes (SM and RM) in a
common function and uses a loop which deals with all the arguments of the
sequence. This patch improves xterm and vt100 compability.
---
 st.c |  180 ++++++++++++++++++++++++++++--------------------------------------
 1 file changed, 76 insertions(+), 104 deletions(-)

This will really be needed when there is a full 256 color support.

This sequence performs "Cursor Forward Tabulation <n> tab stops", which
although is not present in vt100 or vt102, xterm accepts it.
---
 st.c |    5 +++++
 1 file changed, 5 insertions(+)

This sequence clears tab stops in the terminal. If the argument is not present
or is zero, then removes the tab stop of the current horizontal position. If
the argument is 3 then removes all the tab stops of the terminal. It was
necessary modify the terminfo entry tbc, because it has \E[2g instead of the
correct \E[3g.

Signed-off-by: Roberto E. Vargas Caballero <k0ga@shike2.com>
---
 st.c    |   12 ++++++++++++
 st.info |    2 +-
 2 files changed, 13 insertions(+), 1 deletion(-)

This sequence adds a new tab stop in the current horizontal position. This
means that tputtab must be look for the next tab stop in the tabs array
instead of using a hard coded value offset. Also, CHT sequence XXX message
is removed because it is not a vt10x sequence (as far as I know it is a
vt50x sequence), and it is not implemented by linux virtual terminal neither
by xterm.

Signed-off-by: Roberto E. Vargas Caballero <k0ga@shike2.com>
---
 st.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

Tabs stop are simulated in st using a fixed size of 8, always, without be
worried about sequences changing the tab stops. A user can put a tab stop in
each horizontal position of the screen, so we need at least one flag for
each column of the screen. In the same way as dirty flags is used for the
rows, it is used a bool dinamic array.

Signed-off-by: Roberto E. Vargas Caballero <k0ga@shike2.com>
---
 st.c |   22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)