Linux Webview Positioning Fix

Problem Description

On Linux systems using GTK, Tauri applications with multiple webviews experience a critical positioning bug where webviews ignore their position and size settings. Instead of being positioned at specified coordinates, all webviews stack vertically in the default layout container.

Symptoms

Webviews ignore set_webview_position() and set_webview_size() calls
Multiple webviews stack vertically instead of positioning absolutely
Works correctly on Windows and macOS, but fails on Linux
Issue affects all GTK-based Tauri applications using multiwebview feature

Affected Versions

Tauri: v2.x (all versions up to at least v2.9.x)
tao: v0.33.x and later
Platform: Linux (GTK-based systems)

Related Issues

Root Cause

The issue stems from GTK's container system and how Tauri manages child webviews:

GTK Container Behavior: Tauri on Linux uses gtk::Box (vertical box layout) as the default container for webviews
Automatic Layout: gtk::Box automatically manages child widget positioning, overriding any manual position settings
Missing Absolute Positioning: GTK requires gtk::Fixed container for absolute positioning of child widgets
API Gap: The tao windowing library didn't expose the gtk::Fixed container to Tauri

Technical Details

// PROBLEM: Using gtk::Box (automatic layout)
let vbox = window.default_vbox().unwrap();
webview_builder.build_gtk(vbox)
// GTK's Box widget ignores absolute positioning

// SOLUTION: Using gtk::Fixed (absolute positioning)
let fixed = window.fixed().unwrap();
webview_builder.build_gtk(fixed)
// GTK's Fixed widget respects absolute positioning

The Fix

The fix requires coordinated changes across two libraries:

1. tao (Windowing Library)

Repository: https://github.com/Benjaminlooi/tao

Branch: multiwebview-fix

Changes:

Add fixed: Option<gtk::Fixed> field to Window struct
Create gtk::Fixed container during window initialization
Expose fixed() method in WindowExtUnix trait API

Modified Files:

src/platform/unix.rs - Added public API
src/platform_impl/linux/window.rs - Implementation

Code Changes:

// src/platform/unix.rs
pub trait WindowExtUnix {
    // ... existing methods ...
    fn fixed(&self) -> Option<&gtk::Fixed>;
}

impl WindowExtUnix for Window {
    fn fixed(&self) -> Option<&gtk::Fixed> {
        self.window.fixed.as_ref()
    }
}

// src/platform_impl/linux/window.rs
pub struct Window {
    pub(crate) window: gtk::ApplicationWindow,
    pub(crate) default_vbox: Option<gtk::Box>,
    pub(crate) fixed: Option<gtk::Fixed>,  // NEW FIELD
    // ... other fields ...
}

// During window creation:
let fixed = match default_vbox {
    Some(ref vbox) => {
        let fixed = gtk::Fixed::new();
        vbox.pack_start(&fixed, true, true, 0);
        fixed.show_all();
        Some(fixed)
    },
    None => None,
};

2. tauri-runtime-wry (Tauri Runtime)

Repository: https://github.com/Benjaminlooi/tauri

Branch: multiwebview-fix

Changes:

Replace window.default_vbox() with window.fixed() in webview creation
Add Cargo.toml patch to use patched tao

Modified Files:

crates/tauri-runtime-wry/src/lib.rs (lines 4763, 4788)
crates/tauri-runtime-wry/Cargo.toml

Code Changes:

// crates/tauri-runtime-wry/src/lib.rs

// BEFORE (line 4763):
let vbox = window.default_vbox().unwrap();
webview_builder.build_gtk(vbox)

// AFTER:
let fixed = window.fixed().unwrap();
webview_builder.build_gtk(fixed)

// Same change on line 4788

# crates/tauri-runtime-wry/Cargo.toml
[patch.crates-io]
tao = { git = "https://github.com/Benjaminlooi/tao.git", branch = "multiwebview-fix" }

Implementation in Your Project

Using the Patches

Add the following to your Cargo.toml:

# Git patches for Linux multiwebview positioning fix
# See: https://github.com/tauri-apps/tauri/issues/10420
[patch.crates-io]
tao = { git = "https://github.com/Benjaminlooi/tao.git" }
tauri-runtime = { git = "https://github.com/Benjaminlooi/tauri.git" }
tauri-runtime-wry = { git = "https://github.com/Benjaminlooi/tauri.git" }
tauri-utils = { git = "https://github.com/Benjaminlooi/tauri.git" }

Note: The patches track the default branch and will stay compatible with your Tauri version's dependency requirements.

Update Dependencies

# Update to use patched versions
cargo update -p tao -p tauri-runtime -p tauri-runtime-wry -p tauri-utils

# Verify patches are applied
cargo tree -p tao --depth 0
cargo tree -p tauri-runtime-wry --depth 0

You should see output like:

tao v0.33.0 (https://github.com/Benjaminlooi/tao.git#...)
tauri-runtime-wry v2.6.0 (https://github.com/Benjaminlooi/tauri.git#...)

Build and Test

# Clean build to ensure patches are applied
cargo clean
cargo build

# Or run development server
npm run tauri dev

Verification

Testing the Fix

Create Multiple Webviews: Create 2-3 webviews with different positions
Set Explicit Positions: Use set_webview_position() with distinct coordinates
Verify Layout: Webviews should appear at specified positions, not stacked vertically

Expected Behavior

Before Fix:

┌─────────────────┐
│   Webview 1     │
├─────────────────┤
│   Webview 2     │  <- All stacked vertically
├─────────────────┤
│   Webview 3     │
└─────────────────┘

After Fix:

┌─────────────────────────┐
│  ┌────┐        ┌────┐   │
│  │ W1 │        │ W2 │   │  <- Positioned as specified
│  └────┘        └────┘   │
│          ┌────┐         │
│          │ W3 │         │
│          └────┘         │
└─────────────────────────┘

Version Compatibility

Tested Versions

Component	Version	Status
tauri	2.5.1	✅ Working
tao	0.33.0	✅ Patched
tauri-runtime-wry	2.6.0	✅ Patched
GTK	3.24+	✅ Compatible

Future Versions

The patches are maintained on GitHub and should work with future Tauri versions until the fix is merged upstream. Monitor the issue tracker for official releases that include this fix.

Troubleshooting

Patches Not Applied

Symptom: Cargo warnings about unused patches

warning: Patch `tao v0.33.0` was not used in the crate graph

Solution: Version mismatch. Check your Tauri version's dependency requirements:

cargo tree -i tao
cargo tree -i tauri-runtime-wry

Update the patch git URLs to match the required versions, or pin your Tauri version.

Build Errors

Symptom: Trait bound errors or missing methods

Solution:

Clean build directory: cargo clean
Update dependencies: cargo update
Verify patches: cargo tree -p tao

Webviews Still Stacking

Symptom: Webviews still appear vertically stacked after applying patches

Possible Causes:

Old build artifacts - Run cargo clean
Patches not applied - Verify with cargo tree
Platform-specific code path - Check that your code runs the GTK path
Window created with with_default_vbox(false) - Fix requires default vbox enabled

Webviews Lose Position on Window Resize

Symptom: Webviews move to the top-left corner when the main window is resized

Root Cause: Using separate set_position() and set_size() calls doesn't properly trigger GTK Fixed container repositioning

Solution: Use set_bounds() instead, which properly handles GTK Fixed container updates:

// BEFORE (incorrect for GTK Fixed)
webview.set_position(Position::Logical(position))?;
webview.set_size(Size::Logical(size))?;

// AFTER (correct for GTK Fixed)
let bounds = Rect {
    position: Position::Logical(position),
    size: Size::Logical(size),
};
webview.set_bounds(bounds)?;

When the window is resized, the frontend must recalculate webview positions and call set_bounds() to update all webviews. The set_bounds() method internally calls gtk_fixed_move() and properly updates child widget positions within the Fixed container.

Implementation in ChenChen:

Frontend listens for window resize events (src/routes/+page.svelte:38)
Debounced handler recalculates panel bounds (src/routes/+page.svelte:86-95)
Backend command uses set_bounds() for updates (src-tauri/src/commands.rs:289-291)

Performance Impact

The fix has minimal performance impact:

Memory: One additional gtk::Fixed widget per window (~negligible)
CPU: No measurable overhead
Compatibility: No breaking changes to existing API

Contributing

If you encounter issues with these patches:

Bug Reports: Open issues on the respective GitHub repositories
Improvements: Submit PRs to the patch branches
Upstream: Encourage Tauri maintainers to merge the fix

Credits

Original Issue: Reported by community members on GitHub issues #10420, #13071
Fix Implementation: Based on community investigation and GTK documentation
Patches Maintained By: Benjaminlooi (https://github.com/Benjaminlooi)

References

License

These patches maintain the same license as the original Tauri and tao projects (Apache-2.0/MIT).

Last Updated: 2025-11-19 Tauri Version: 2.9.3 Status: Active patch with resize fix, awaiting upstream merge

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Linux Webview Positioning Fix

Problem Description

Symptoms

Affected Versions

Related Issues

Root Cause

Technical Details

The Fix

1. tao (Windowing Library)

2. tauri-runtime-wry (Tauri Runtime)

Implementation in Your Project

Using the Patches

Update Dependencies

Build and Test

Verification

Testing the Fix

Expected Behavior

Version Compatibility

Tested Versions

Future Versions

Troubleshooting

Patches Not Applied

Build Errors

Webviews Still Stacking

Webviews Lose Position on Window Resize

Performance Impact

Contributing

Credits

References

License

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Linux Webview Positioning Fix

Problem Description

Symptoms

Affected Versions

Related Issues

Root Cause

Technical Details

The Fix

1. tao (Windowing Library)

2. tauri-runtime-wry (Tauri Runtime)

Implementation in Your Project

Using the Patches

Update Dependencies

Build and Test

Verification

Testing the Fix

Expected Behavior

Version Compatibility

Tested Versions

Future Versions

Troubleshooting

Patches Not Applied

Build Errors

Webviews Still Stacking

Webviews Lose Position on Window Resize

Performance Impact

Contributing

Credits

References

License