Some times the size after a resizing is not an exact multiply of a number of
characters, so redrawn the screen using the lines and columns of the neww
size can cause that some old graphics keep in the screen. Solution is clean
all the windows with the background color.
---
 st.c |    3 +++
 1 file changed, 3 insertions(+)

st selection don't insert in the selection position whose value is not
set. This is correct for the positions in the end of the line, but cause
some problems in the beginning. For example echo -e 'a\tb' will print in the
screen:

a	b

but after selecting and copying in some place you get:

ab

because positions from 1 to 7 don't have any value. This patch deals all
positions without value as blank (even at the end of the line).
---
 st.c |   17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

---
 st.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

malloc and realloc are called through xmalloc and xrealloc, so calloc should
be called through xcalloc.
---
 st.c |   13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

In previous commits draw was removed from all the X events, but I forgot do
it in resize.
---
 st.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

After the commit named "Remove timeout in the main loop", selection is not
working in the proper way. After selecting something, press mouse button in
a line outside of selection causes an incorrect highlight. This patch fix
the problem forcing a draw after the press event, but this is only a fast
hack. Real solution means rewriting selection code.
---
 st.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

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(+)