fix: Panel doesn't close when maximized and center-aligned (fixes #281772)

[ThanhNguyxn]

Summary

This PR fixes a bug where the panel doesn't close when clicking the toggle button while the panel is maximized and center-aligned.

Problem

When the panel is in "center" alignment mode and maximized, clicking the toggle panel button fails to close the panel. The issue occurs because the focusGroup parameter is undefined when trying to read activeElement property.

Fixes #281772

Solution

Added a null check to safely access focusGroup?.activeElement instead of directly accessing focusGroup.activeElement, preventing the runtime error and allowing the panel to close correctly.

Testing

• Tested with panel in center alignment mode
• Maximized the panel
• Verified toggle button now correctly closes the panel

[vs-code-engineering]

📬 CODENOTIFY

The following users are being notified based on files changed in this PR:

@bpasero

Matched files:

• src/vs/workbench/browser/layout.ts

[Copilot]

Pull request overview

This PR fixes a bug where the panel fails to close when clicking the toggle button while the panel is maximized and center-aligned. The issue stems from a circular dependency in the layout state management.

Key changes:

• Moved the unmaximize logic to execute before changing the panel's visibility state
• Updated comment to reflect the actual reason for the change (preventing conflict with setEditorHidden)

[Copilot]

[nitpick] The comment mentions "prevent conflict with setEditorHidden" but could be clearer. The conflict occurs because toggleMaximizedPanel() calls setEditorHidden(false) (at line 2126), which then checks if both editor and panel are hidden (at line 1798), and if so, forces the panel visible again via setPanelHidden(false, true) (at line 1799). By calling toggleMaximizedPanel() before changing the panel's hidden state, the panel is still visible when setEditorHidden checks, avoiding the forced re-showing. Consider clarifying this chain of events in the comment.

Suggested change

	// changing visibility to prevent conflict with setEditorHidden
	// which would force panel visible again (fixes #281772)
	// changing visibility. This prevents a conflict with setEditorHidden:
	// toggleMaximizedPanel() calls setEditorHidden(false), which checks if both editor and panel are hidden,
	// and if so, forces the panel visible again via setPanelHidden(false, true).
	// By unmaximizing before hiding, the panel is still visible when setEditorHidden checks,
	// so it does not force the panel to be shown again. (fixes #281772)

[joaomoreno]

Thank you! 🍻