Conditional Bindkey Function

Hi Everyone,

Please help me figure this out.

For example, I have an a() function that's bound to the <key>a in the layout.

then I also have another function b() that's bound to the <key>b in the layout.

Conditions:

1. function b() will only be activated once the function a() is activated.
2. function a() will be deactivated by pressing other bindkeys (example bindkeys q, x , f etc.)
3. function b() will return to its default command function default() when Function a() is deactivated.
4. the form xyz() that's bound to the <key> F3 will open once the function a() is activated. - similar to default functions that use f3 to open a form.

Thank you in advance for your help.