fix(ui): prevent crash when window size is zero

[ty-yqs]

Description

This PR addresses a critical issue reported in #7650 where setting a VM window's bounds to {0, 0, 0, 0} (e.g., via AppleScript or automation) causes the application to crash. This crash would forcefully terminate all running virtual machines, potentially leading to data loss.

The root cause was that the standard NSWindow allows setting a zero frame size, which subsequently causes failures in the layout or rendering pipeline (e.g., coordinate calculations resulting in NaN or division by zero).

Changes

• New File: Platform/macOS/Display/VMDisplayWindow.swift
  • Implemented a custom NSWindow subclass named VMDisplayWindow.
  • Added sanitizeFrame(_:) logic to enforce a minimum safe window size (400x300) and prevent invalid dimensions (width/height <= 0).
  • Overrode setFrame methods to intercept all resize attempts and apply sanitized bounds.
  • Added logging to warn developers/users when invalid window bounds are attempted.
• Modified: Platform/macOS/Display/Base.lproj/VMDisplayWindow.xib
  • Updated the window class from NSWindow to the custom VMDisplayWindow to activate the safe resizing logic.

Testing Instructions

1. Launch UTM and start a virtual machine.
2. Open Script Editor.app and run the following AppleScript (replace "vmname" with your VM's window title):

   tell application "UTM"
       set bounds of window "vmname" to {0, 0, 0, 0}
   end tell

3. Expected Result:
   • The app does not crash.
   • The VM window resizes to the minimum allowed size (400x300).
   • A warning is logged in the console: "Attempted to set invalid window width...".

Related Issue

Fixes #7650

[Copilot]

Pull request overview

Adds a macOS NSWindow subclass to sanitize invalid VM display window frame sizes (notably {0,0,0,0} via AppleScript) to prevent UI crashes that can terminate running VMs.

Changes:

• Introduces VMDisplayWindow (NSWindow subclass) that clamps window frames to a minimum size during setFrame calls and logs warnings for invalid dimensions.
• Updates VMDisplayWindow.xib to use VMDisplayWindow as the window’s custom class so the sanitization applies at runtime.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
Platform/macOS/Display/VMDisplayWindow.swift	Adds NSWindow subclass that clamps frame size and logs invalid resize attempts.
Platform/macOS/Display/Base.lproj/VMDisplayWindow.xib	Switches the window in the VM display nib from NSWindow to VMDisplayWindow.

[Copilot]

Overriding minSize to always return the hard-coded 400x300 breaks existing callers that intentionally set window.minSize at runtime (e.g. VMDisplayAppleDisplayWindowController.updateWindowFrame() sets window.minSize based on content/dynamic resolution). AppKit will consult this overridden getter, so the effective minimum size becomes fixed and those code paths can no longer raise the minimum when needed. Consider removing this override and instead (a) set super.minSize to the base minimum in awakeFromNib/init, and (b) when sanitizing frames, clamp to max(super.minSize, baseMinimum) so higher minimums set by controllers are still respected.

[Copilot]

sanitizeFrame(_:) clamps against the hard-coded constants rather than the window’s current minSize. This can conflict with runtime minimum sizes that other parts of the app set on the window (for example to enforce an aspect ratio or content-driven minimum). Consider clamping against max(baseMinimum, super.minSize) so the crash fix still applies while preserving larger minimum sizes configured elsewhere.

[Copilot]

sanitizeFrame(_:) doesn’t handle NaN/±infinity dimensions: comparisons like width < kMinWindowWidth are false for NaN, so an invalid incoming frame can bypass clamping and still propagate into AppKit. If the goal is to prevent crashes from invalid geometry, treat non-finite sizes as invalid and clamp them to the minimum as well (e.g. check isFinite before comparing).

Suggested change

	// Check for invalid or too small dimensions
	if frame.size.width < kMinWindowWidth {
	// Log warning only if it's significantly invalid (e.g. 0 or negative)
	if frame.size.width <= 0 {
	logger.warning("Attempted to set invalid window width: \(frame.size.width). Clamping to \(kMinWindowWidth).")
	}
	frame.size.width = kMinWindowWidth
	}
	if frame.size.height < kMinWindowHeight {
	if frame.size.height <= 0 {
	logger.warning("Attempted to set invalid window height: \(frame.size.height). Clamping to \(kMinWindowHeight).")
	// Check for invalid or too small dimensions, including non-finite values
	let width = frame.size.width
	if !width.isFinite || width < kMinWindowWidth {
	// Log warning only if it's significantly invalid (e.g. non-finite, 0 or negative)
	if !width.isFinite || width <= 0 {
	logger.warning("Attempted to set invalid window width: \(width). Clamping to \(kMinWindowWidth).")
	}
	frame.size.width = kMinWindowWidth
	}
	let height = frame.size.height
	if !height.isFinite || height < kMinWindowHeight {
	if !height.isFinite || height <= 0 {
	logger.warning("Attempted to set invalid window height: \(height). Clamping to \(kMinWindowHeight).")