Linux: Split resize area too large

[Sirius902]

Issue

The area in which you can click and drag to resize splits is too large, it is even possible to resize the splits without the cursor showing that it may be resized. With the horizontal split configuration shown below, the offending area seems to be larger on the edge bordering the right split. In the video, you can see that I can select starting from the third character from the left on the split border but not any closer to the border.

I can only reproduce this on my Linux box, not on macOS.

split-shenanagins.mp4

Expectation

I would expect the following regardless of the OS in use, currently these expectations seem to be met on macOS but not with my Linux setup:

• It is possible to select characters bordering splits using the mouse (difficult right now due to this issue).
• Clicking and dragging will not resize splits unless the cursor is also changed to reflect this.
• The area you can click and drag to resize splits is appropriately sized to the split border.

Configuration

Running on NixOS with GNOME.

ghostty built from flake with commit fa3896b.

[mitchellh]

I wonder if this will end up being a GTK issue and not ours. We're using a native GTK widget for this and as far as I know we don't define any of this, but its worth investigation.

[jcollie]

Yeah, I'd say that's a "feature" of GTK. Not even sure how you'd change that without some deep GTK magic. The workaround is to use the mouse to select from right-to-left, rather than selecting from left-to-right.

[mitchellh]

Yep, my research is that this is just GTK doing this. I think this is acceptable.

[akhilerm]

Facing the same issue. This means that sometime it is difficult to select characters and text that start at the left of the split.

[carragom]

Having the same problem, reported as duplicate in #5630. Bit sad to hear this is acceptable.

[daviewales]

It is strange to me that this is a 'GTK issue', when other GTK apps on my system don't exhibit this behaviour. (Unless it's a GTK3 vs GTK4 issue? Or a Libadwaita issue?) I have noted in a related discussion that Nemo for example has a split divider between the left sidebar and the directory view, and it works as expected. In particular, the drag surface in Nemo and the drag cursor indicator are consistent, unlike Gostty. The drag surface in Nemo is also much narrower then in Ghostty.
See: #5655 (reply in thread)

Edit: gtk-adwaita = false doesn't fix it.

[daviewales]

Confirming that this is indeed a Gtk 4 issue:

The following minimal Gtk 3 app does not have the issue:

# https://stackoverflow.com/a/69773849

import gi

gi.require_version("Gtk", "3.0")
from gi.repository import Gtk

class App(Gtk.Window):
    """The window."""

    def __init__(self):
        super().__init__()
        self.connect("delete-event", Gtk.main_quit)

        self.set_default_size(200, 200)

        # The paned window
        self.paned = Gtk.Paned()
        self.add(self.paned)

        # Widets to put in the paned window
        self.label = Gtk.Label(label="Sidebar")
        self.paned.add1(self.label)

        self.button = Gtk.Button.new_with_label("Something else")
        self.paned.add2(self.button)

        self.show_all()

App()
Gtk.main()

Updating this minimal app to Gtk 4, the issue appears:

# https://stackoverflow.com/a/69773849
# https://github.com/Taiko2k/GTK4PythonTutorial

import gi
gi.require_version('Gtk', '4.0')
from gi.repository import Gtk

class MainWindow(Gtk.ApplicationWindow):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self.set_default_size(200, 200)

        # The paned window
        self.paned = Gtk.Paned()
        self.set_child(self.paned)

        # Widets to put in the paned window
        self.label = Gtk.Label(label="Sidebar")
        self.paned.set_start_child(self.label)

        self.button = Gtk.Button.new_with_label("Something else")
        self.paned.set_end_child(self.button)

class MyApp(Gtk.Application):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.connect('activate', self.on_activate)

    def on_activate(self, app):
        self.win = MainWindow(application=app)
        self.win.present()

app = MyApp(application_id="com.example.GtkApplication")
app.run()

The issue remains if we use Adwaita:

6c6,7
< from gi.repository import Gtk
---
> gi.require_version('Adw', '1')
> from gi.repository import Gtk, Adw
25c26,27
< class MyApp(Gtk.Application):
---
>
> class MyApp(Adw.Application):

Edit: I've opened an issue with GTK: https://gitlab.gnome.org/GNOME/gtk/-/issues/7330
Edit: That was a duplicate. Here's the original GTK issue: https://gitlab.gnome.org/GNOME/gtk/-/issues/4484

[jcollie]

Keeping this open since the issue isn't 100% solved yet.

[daviewales]

I've added some partial progress to a discussion here: #6059. Suggestions welcome!