Description of issues:
1 - the count of selected items is incorrect after performing mass delete in Configuration => Hosts => Triggers view.
2 - If the Configuration => Hosts => Triggers view is opened in 2 tabs and in 1st tab one of the triggers is deleted, then in the 2nd tab after attempting to delete this trigger together with some other trigger the count of selected elements is returned incorrectly and the 2nd trigger is not removed after pressing the Delete button for the 2nd time.

Steps to reproduce:
1 - Create a host.
2 - Create 3 items under the host.
3 - Create a trigger for each item.
4 - Open the Configuration => Hosts => (Your host name) => Triggers view in 2 tabs of the browser.
5 - In the 1st tab select 2 triggers and press "Delete" button.
Result 1: the count of selected elements in the bottom left corner is still 2, even though no actual triggers are selected.
6 - Switch to the 2nd tab with the trigger list.
7 - Select all 3 triggers and press button "Delete"
Result 2: only the item that was not deleted previously is still returned in the list, but the count of selected items is still equal to 3.
8 - press the "Delete" button again to delete the remaining trigger.
Result 3: The item is not deleted.

Expected:
Result 1: The count of selected items should be equal to zero after deleting 2 triggers i the 1st tab.
Result 2: It is ok that the item is still in the list, but the number of selected elements should be equal to 1.
Result 3: After pressing the button "Delete" for the 2nd time the remaining trigger should be successfully deleted.

Example: