Bug Description:

The chat UI has various issues when using the chat in a secondary window. This was encountered with version 1.59.1 of the Theia IDE using theme Theia (Dark).

• The file variable's file picker does not have any content
• Auto complete highlight for variable/agent selection does not work
• Text selection in the input field is not visible
• Cursor in the input field is not visible

Steps to Reproduce:

1. Open AI Chat window: View -> Chat
2. Click button "Move View to Secondary Window" in its toolbar
3. Mark text, enter agent and file variable

Additional Information

• Operating System: Ubuntu 24.04
• Theia Version: 1.59.1 (Theia IDE)