Bugzilla

**Found in**
* 106.0b2

**Affected versions**
* 106.0b2
* 107.0a1

**Tested platforms**
* Affected platforms: macOS12 ,11/ Windows 10,11 / Ubuntu 22

**Steps to reproduce**
1. Launch FF .
2. Open multiple tabs.
3. Hold Control/Command button pressed, and starting with FF View button, select multiple tabs.
4. Hold Shift button pressed and select a range between tabs.
5. Go in Firefox View, hold Shift and select another range of tabs.
6. Go back to the tab strip , and select another range of tabs(this time without having FF View in focus or in tab range).

**Expected result**
* The Shift+Click tabs range selection works without any issues.

**Actual result**
* The Shift+Click tabs range selection no longer works after performing the steps from STR.

**Regression Range**
* First bad: 2022-09-16
* Last good: 2022-09-15
* [Pushlog](https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=fdf43cbc3e8d50998f16c38a5b97494a78ccd210&tochange=b8aafd1ec4ed11fad9dbcd6451b77c3371fe6b2a
* Potentially regressed by: 1790593

**Other notes**
* After reproducing these steps, the tab range multi select is no longer functional for the entirety of the session(restart required).
* After performing these steps, the Firefox account becomes corrupted, displaying the "Send 0 tabs to device>" option. [Image](https://drive.google.com/file/d/1IZ0Tf1mGjwXT5U2omwcp2XgKlxogwNrr/view?usp=sharing) of the issue
* When performing the required steps to reproduce this issue, the following error is displayed in browser console:
```
Uncaught TypeError: aTab is undefined
    addToMultiSelectedTabs chrome://browser/content/tabbrowser.js:5042
    addRangeToMultiSelectedTabs chrome://browser/content/tabbrowser.js:5075
    on_mousedown chrome://browser/content/tabbrowser-tab.js:379
    handleEvent chrome://global/content/customElements.js:463
```

**Found in**
* 106.0b2

**Affected versions**
* 106.0b2
* 107.0a1

**Tested platforms**
* Affected platforms: macOS12 ,11/ Windows 10,11 / Ubuntu 22

**Steps to reproduce**
1. Launch FF .
2. Open multiple tabs.
3. Hold Control/Command button pressed, and starting with FF View button, select multiple tabs.
4. Hold Shift button pressed and select a range between tabs.
5. Go in Firefox View, hold Shift and select another range of tabs.
6. Go back to the tab strip , and select another range of tabs(this time without having FF View in focus or in tab range).

**Expected result**
* The Shift+Click tabs range selection works without any issues.

**Actual result**
* The Shift+Click tabs range selection no longer works after performing the steps from STR.

**Regression Range**
* First bad: 2022-09-16
* Last good: 2022-09-15
* [Pushlog](https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=fdf43cbc3e8d50998f16c38a5b97494a78ccd210&tochange=b8aafd1ec4ed11fad9dbcd6451b77c3371fe6b2a)
* Potentially regressed by: 1790593

**Other notes**
* After reproducing these steps, the tab range multi select is no longer functional for the entirety of the session(restart required).
* After performing these steps, the Firefox account becomes corrupted, displaying the "Send 0 tabs to device>" option. [Image](https://drive.google.com/file/d/1IZ0Tf1mGjwXT5U2omwcp2XgKlxogwNrr/view?usp=sharing) of the issue
* When performing the required steps to reproduce this issue, the following error is displayed in browser console:
```
Uncaught TypeError: aTab is undefined
    addToMultiSelectedTabs chrome://browser/content/tabbrowser.js:5042
    addRangeToMultiSelectedTabs chrome://browser/content/tabbrowser.js:5075
    on_mousedown chrome://browser/content/tabbrowser-tab.js:379
    handleEvent chrome://global/content/customElements.js:463
```