Auto-follow process when selecting which signal to use when killing a process.

This avoids killing the wrong process.

ProcessList.c

@@ -236,6 +236,7 @@ ProcessList* ProcessList_new(UsersTable* usersTable) {
    this->detailedCPUTime = false;
    this->countCPUsFromZero = false;
    this->treeStr = NULL;
+   this->following = -1;
 
    return this;
 }
@@ -915,7 +916,7 @@ void ProcessList_rebuildPanel(ProcessList* this, bool flags, int following, bool
    }
 
    int currPos = Panel_getSelectedIndex(this->panel);
-   pid_t currPid = following ? following : 0;
+   pid_t currPid = following != -1 ? following : 0;
    int currScrollV = this->panel->scrollV;
 
    Panel_prune(this->panel);

htop.c

@@ -207,7 +207,16 @@ static Object* pickFromVector(Panel* panel, Panel* list, int x, int y, const cha
    ScreenManager_add(scr, panel, NULL, -1);
    Panel* panelFocus;
    int ch;
+   bool unfollow = false;
+   if (header->pl->following == -1) {
+      Process* p = (Process*)Panel_getSelected(panel);
+      header->pl->following = p ? p->pid : -1;
+      unfollow = true;
+   }
    ScreenManager_run(scr, &panelFocus, &ch);
+   if (unfollow) {
+      header->pl->following = -1;
+   }
    ScreenManager_delete(scr);
    Panel_move(panel, 0, y);
    Panel_resize(panel, COLS, LINES-y-1);