This PR fixes two critical issues with frame dragging behavior in the canvas:

Issues Fixed

1. Branch Switching Dragging Wrong Frames

When a user created a new branch and attempted to drag the webframe topbar, the system would drag frames from the original branch instead of the current branch. This occurred because the dragging logic relied on previously selected frames rather than ensuring the clicked frame was properly selected first.

2. Window Selection Not Updating During Drag

When a user had one window selected and tried to drag a different adjacent window, the system would continue dragging the originally selected frames instead of the clicked frame. The topbar would visually respond to the hover but the actual drag operation would move the wrong frames.

Root Cause

The problem was in two areas:

1. TopBar Component: The handleMouseDown function immediately started dragging based on editorEngine.frames.selected without ensuring the clicked frame was selected first.

2. FramesManager: The select method was toggling frame selection state (!this.isSelected(frame.id)) even for non-multiselect operations, which could unexpectedly deselect already-selected frames.

Solution

Modified Frame Selection Logic

Updated FramesManager.select() to behave more intuitively:

• Without multiselect: Always ensure frames are selected (not toggled)
• With multiselect: Preserve toggle behavior for shift+click operations

Enhanced TopBar Mouse Handling

Updated the handleMouseDown function to select the clicked frame before initiating drag operations when:

• The clicked frame is not currently selected
• It's not a multiselect operation (no shift key)

This ensures the correct frame is always selected before determining which frames to drag.

Behavior Changes

• ✅ Clicking any frame's topbar now immediately selects and drags that specific frame
• ✅ Branch switching followed by dragging now works with the correct branch frames
• ✅ Multiselect functionality with shift+click remains unchanged
• ✅ All existing selection patterns throughout the codebase continue to work

The changes are minimal and surgical, addressing the root cause while preserving all existing functionality.

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