In Linux, Which component decides to open a new window in gedit?

Question

Let's consider that I open a file with the command gedit toto1.txt, a new window shows up with the content of toto1.txt. This sound familiar and usual, however the two following cases are not that straight to undertand: (1) a new command (let's says gedit toto2.txt) open a new tab in the previous window and (2) a new command (let's says gedit toto3.txt) will open a new tab in a new window.

My question is : which component decide to open the new window in case (2) and what are the condition to do so ? Why It did not opened a new window in case (1) ?

Any idea ?

Answer 1

It's gedit itself that makes that decision. Let's take a look at the source code. The function open_files will open a new window when it cannot find an active window (or when the flag --new-window was explicitly specified).

static void
open_files (GApplication            *application,
            gboolean                 new_window,
            ...)
{
        GeditWindow *window = NULL;

        if (!new_window)
        {
                window = get_active_window (GTK_APPLICATION (application));
        }

        if (window == NULL)
        {
                gedit_debug_message (DEBUG_APP, "Create main window");
                window = gedit_app_create_window (GEDIT_APP (application), NULL);

                gedit_debug_message (DEBUG_APP, "Show window");
                gtk_widget_show (GTK_WIDGET (window));
        }

        ...
}

So what's an "active window"? Let's look at get_active_window:

static GeditWindow *
get_active_window (GtkApplication *app)
{
    GdkScreen *screen;
    guint workspace;
    gint viewport_x, viewport_y;
    GList *windows, *l;

    screen = gdk_screen_get_default ();

    workspace = gedit_utils_get_current_workspace (screen);
    gedit_utils_get_current_viewport (screen, &viewport_x, &viewport_y);

    /* Gtk documentation says the window list is always in MRU order */
    windows = gtk_application_get_windows (app);
    for (l = windows; l != NULL; l = l->next)
    {
        GtkWindow *window = l->data;

        if (GEDIT_IS_WINDOW (window) && is_in_viewport (window, screen, workspace, viewport_x, viewport_y))
        {
            return GEDIT_WINDOW (window);
        }
    }

    return NULL;
}

So, the answer is: gedit will open a new window if there's not already a gedit window on screen.

(Well, there could of course be bugs here. I haven't looked very closely. That viewport_x/y stuff looks a bit suspect, as a viewport should have four coordinates: top/bottom/left/right. The code might be confused by multi-monitor setups).