User: if you already have tmux panes as horizontal, how do you switch them to vertical?
Assistant: In `tmux`, if you want to change the layout of your panes from horizontal to vertical, you can use the `select-layout` command to achieve this. Here's how you can do it:

1. **Switch to Vertical Layout:**

   If you have multiple panes open horizontally and you want to switch to a vertical layout, you can use the following tmux command:

   ```bash
   Ctrl+b
   ```

   Then release the keys and press:

   ```bash
   :select-layout even-vertical
   ```

   This command will adjust your panes to be evenly distributed vertically.

2. **Alternative Layouts:**

   `tmux` offers several layout options. Here are some you might find useful:

   - `tiled`: Arranges panes in a tiled layout.
   - `even-horizontal`: Arranges panes evenly in a horizontal layout.
   - `even-vertical`: Arranges panes evenly in a vertical layout.
   - `main-horizontal`: A large horizontal pane on top, with smaller panes below.
   - `main-vertical`: A large vertical pane on the left, with smaller panes on the right.

3. **Manual Resizing:**

   Sometimes, automatic layout adjustments may not suit your needs perfectly. You can manually resize panes using:

   - `Ctrl+b` then `:` and type `resize-pane -R 10` to resize the current pane 10 cells to the right.
   - `Ctrl+b` then `:` and type `resize-pane -L 10` to resize the current pane 10 cells to the left.
   - `Ctrl+b` then `:` and type `resize-pane -U 10` to resize the current pane 10 cells upward.
   - `Ctrl+b` then `:` and type `resize-pane -D 10` to resize the current pane 10 cells downward.

Use these commands to adjust your pane layout as desired. Remember that custom changes can be achieved interactively by simply using `Ctrl+b` followed by arrow keys (`UP/DOWN/LEFT/RIGHT`) to manually resize panes to your liking.
User: that command didn't work, nothing happened
Assistant: If the command `:select-layout even-vertical` did not work as expected, let's go through a few steps to troubleshoot and ensure that the panes are switching layouts correctly:

1. **Ensure Correct Key Combination:**
   - Press `Ctrl+b` to activate tmux's command mode, release both keys, and then press `:` to open the command prompt within tmux. You should see a command-line input at the bottom of the screen.

2. **Check for Errors:**
   - After you enter the command `select-layout even-vertical`, look for any error messages that might be displayed at the bottom of the tmux window.

3. **Try Alternate Layouts:**
   - If `even-vertical` isn't responding, try switching to another predefined layout, such as:
     ```bash
     :select-layout main-vertical
     ```
   - This might help check if the issue is specific to the 'even-vertical' layout.

4. **Manual Resizing as a Test:**
   - Try resizing one of the panes manually to see if the tmux session is responsive:
     - Use `Ctrl+b` followed by `[` or arrow keys to navigate or resize panes interactively.
     - Use `Ctrl+b` followed by `:` and enter `resize-pane -R 10` to resize.

5. **Verify Command Entry:**
   - Ensure that you are entering the command without any typos or extra spaces.
   - You should see a visual change in layout if the command is entered correctly.

6. **Session Configuration:**
   - Check if there are any custom configurations in your `.tmux.conf` file that may affect pane layouts.
   - Reload the configuration using `Ctrl+b` followed by `:` and typing `source-file ~/.tmux.conf`.

If none of these steps work, please check if there are any tmux-specific settings or custom scripts that could be interfering. Alternatively, restarting the tmux session might help resolve unusual behavior.
User: how do I copy text from a tmux pane using the mouse?
Assistant: