[dev] [st] [patch] alternate screen selection bugfix

[p37sitdu]

To trace the glitch, I added
    fprintf(stderr, "%d %d\n", sel.alt, !!IS_SET(MODE_ALTSCREEN));
into the draw() function.

What happens:
1. Start st. Type something: both sel.alt and IS_SET(MODE_ALTSCREEN)
are 0.
2. Run "man man".  MODE_ALTSCREEN is set to 1.
3. Press LMB. sel.alt is 0, MODE_ALTSCREEN is 1, selection is not
displayed because of the '(sel.alt != 0) ^ alt)' check.
4. Release mouse: sel.alt is set to 1, but selection is still not
displayed.
5. Select again: everything is ok.

After I quit "man", MODE_ALTSCREEN is set to 0 and the same thing
happens again, now sel.alt is 1. So selection is displayed only the
second time.

The problem is that sel.alt is set to IS_SET(MODE_ALTSCREEN) only when
selcopy is called, i.e. when mouse button is released. So I moved
"sel.alt = IS_SET(MODE_ALTSCREEN)" to getbuttoninfo.

Patch is attached.

I also made IS_SET always return 0 and 1 to make things simplier.

diff --git a/st.c b/st.c
index 900b567..04515dc 100644
--- a/st.c
+++ b/st.c
@@ -73,7 +73,7 @@
 #define BETWEEN(x, a, b)  ((a) <= (x) && (x) <= (b))
 #define LIMIT(x, a, b)    (x) = (x) < (a) ? (a) : (x) > (b) ? (b) : (x)
 #define ATTRCMP(a, b) ((a).mode != (b).mode || (a).fg != (b).fg || (a).bg != 
(b).bg)
-#define IS_SET(flag) (term.mode & (flag))
+#define IS_SET(flag) ((term.mode & (flag)) != 0)
 #define TIMEDIFF(t1, t2) ((t1.tv_sec-t2.tv_sec)*1000 + 
(t1.tv_usec-t2.tv_usec)/1000)
 
 #define VT102ID "\033[?6c"
@@ -624,6 +624,7 @@ selected(int x, int y) {
 
 void
 getbuttoninfo(XEvent *e) {
+       sel.alt = IS_SET(MODE_ALTSCREEN);
        sel.ex = x2col(e->xbutton.x);
        sel.ey = y2row(e->xbutton.y);
 
@@ -722,7 +723,6 @@ selcopy(void) {
                }
                *ptr = 0;
        }
-       sel.alt = IS_SET(MODE_ALTSCREEN);
        xsetsel(str);
 }
 
@@ -869,16 +869,17 @@ bmotion(XEvent *e) {
                return;
        }
 
-       if(sel.mode) {
-               oldey = sel.ey;
-               oldex = sel.ex;
-               getbuttoninfo(e);
+       if(!sel.mode)
+               return;
 
-               if(oldey != sel.ey || oldex != sel.ex) {
-                       starty = MIN(oldey, sel.ey);
-                       endy = MAX(oldey, sel.ey);
-                       tsetdirt(starty, endy);
-               }
+       oldey = sel.ey;
+       oldex = sel.ex;
+       getbuttoninfo(e);
+
+       if(oldey != sel.ey || oldex != sel.ex) {
+               starty = MIN(oldey, sel.ey);
+               endy = MAX(oldey, sel.ey);
+               tsetdirt(starty, endy);
        }
 }
 
@@ -1510,7 +1511,7 @@ tsetmode(bool priv, bool set, int *args, int narg) {
                        case 1049: /* = 1047 and 1048 */
                        case 47:
                        case 1047: {
-                               alt = IS_SET(MODE_ALTSCREEN) != 0;
+                               alt = IS_SET(MODE_ALTSCREEN);
                                if(alt)
                                        tclearregion(0, 0, term.col-1, 
term.row-1);
                                if(set ^ alt)           /* set is always 1 or 0 
*/
@@ -2603,9 +2604,9 @@ drawregion(int x1, int y1, int x2, int y2) {
        int ic, ib, x, y, ox, sl;
        Glyph base, new;
        char buf[DRAW_BUF_SIZ];
-       bool ena_sel = sel.bx != -1, alt = IS_SET(MODE_ALTSCREEN) != 0;
+       bool ena_sel = sel.bx != -1;
 
-       if((sel.alt != 0) ^ alt)
+       if(sel.alt ^ IS_SET(MODE_ALTSCREEN))
                ena_sel = 0;
        if(!(xw.state & WIN_VISIBLE))
                return;