Fix issue #129

[fs-sifat]

What is it?

• [x] Bugfix (user facing)
• [ ] Feature request (user facing)
• [ ] Codebase improvement (dev facing)

Description of the changes in your PR

• Toggle viewPager.isUserInputEnabled when ToDoManager is focused and unfocused, so that the user can't swipe to another window

Flaws

• Does expose a private variable(viewPager in LauncherActivity.kt) to public

Fixes the following issue(s)

• 129

[iamrasel]

As I am unable to produce such issue on my device, I can't check if this solves the issue. But I do hope for something better.

[fs-sifat]

As I am unable to produce such issue on my device, I can't check if this solves the issue. But I do hope for something better.

To reproduce the issue, simply swipe left/right while the todo manager is visible.