Split Terminals - "focusFollowMouse": true,

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### Windows Terminal version

1.24.11911.0

### Windows build number

10.0.26200

### Other Software

_No response_

### Steps to reproduce

I have "focusFollowMouse": true,

I also have the k8s in a menu with a separator
It will look something like this:

Main Menu
├── Kubernetes Environment A
│ ├── Cluster A - Control Plane 1
│ ├── Cluster A - Control Plane 2
│ ├── Cluster A - Control Plane 3
│ ├── Cluster B - Control Plane 1
│ ├── Cluster B - Control Plane 2
│ ├── Cluster B - Control Plane 3
│ ├── Cluster B - Control Plane 4
----------separator------------
│ ├── Environment A - Control Planes
│ └── Environment A - Worker Nodes

a split pane example:
```
{
"colorScheme": "Raspberry",
"commandline": "wt -w 0 nt -p k8cp-01 ; sp -H -p k8cp-02 ; sp -V -p k8bcp-03",
"guid": "{e4a8f6c3-1451-477e-bf9f-e6aa8bb2b0c2}",
"icon": "C:\\Scripts\\WindowsTerminals\\windows-terminal-icons\\icons\\ubuntu.png",
"name": "K8 Control Planes",
"tabTitle": "k8-cp-1-3"
},
```

The issue is
I want the split screen to open like this every time.
```
-------------------------------------
| k8cp-01 |
-------------------------------------
| k8cp-02 | k8cp-03 |
-------------------------------------
```

The problem is that with focusFollowsMouse set to true, when you mouse leave the menu, you might be over the area of the screen that's not the first pane and you end up with really strange splits

The most common problem is the he mouse is in teh TOP pane and it splits that instead of the bottom pane
you end up with this:
```
-------------------------------------
| k8cp-01 | k8cp-03 |
-------------------------------------
| k8cp-02 |
-------------------------------------
```
Where I have the 4 way split
```
{
"colorScheme": "Raspberry",
"commandline": "wt -w 0 nt -p k8nd-01 ; sp -V -p k8nd-03 ; sp -H -p k8nd-04; mf left ; sp -H -p k8nd-02",
"guid": "{960f4d8d-b89a-4d75-8093-4f28ebb94839}",
"icon": "C:\\Scripts\\WindowsTerminals\\windows-terminal-icons\\icons\\ubuntu.png",
"name": "K8ND Worker Nodes",
"tabTitle": "k8nd-01-04"
}
```
```
-------------------------------------
| k8nd-01 | k8nd-03 |
-------------------------------------
| k8nd-02 | k8nd-04 |
-------------------------------------
````
It ends up looking like this:
```
-------------------------------------
| k8nd-01 | |
------------------| |
| k8nd-02 | k8nd-03 |
------------------| |
| k8nd-04 | |
-------------------------------------
```

### Expected Behavior

I would expect the application:
```
wt -w 0 nt -p k8nd-01 ; sp -V -p k8nd-03 ; sp -H -p k8nd-04; mf left ; sp -H -p k8nd-02
```
to ignore the mouse focus

### Actual Behavior

"focusFollowMouse": true,
is messing with terminal splits

Start by reproducing the split commands from the issue with "focusFollowMouse": true, moving the pointer away from the menu before each split. Compare the resulting pane layouts with the expected diagrams; done when the commands create the requested layouts regardless of the pointer's location.

Written by the indexing model from the issue text.