[UC2] Import presentation from Markdown

Description: Actor should be able to generate presentation from Github Markdown formatted documents. To do so, he can use application for importing Markdown file into a presentation.

Actors: presentation author, reporter, presentation viewer

Prerequisites: application running, no popup dialogs are shown

Basic Flow:

• 1: Actor selects “File” menu from main menu bar.
• 2: User selects “Import...” menu item from “File” menu.
• 3: Application shows dialog for opening Markdown file. Only folders, system locations and Markdown files are visible in dialog.
• 4: Actor selects single markdown file from file system and clicks "Open".
• 5: Application shows import progress.
• 6: After import finish, application shows imported presentation. First slide of the presentation is opened in a window.

Alternative Flows:

• 4a: User clicks "Cancel".
  • 4a1: Dialog for opening file closes.

• 3a: Application detects that opened document contains unsaved changes
  • 3a1: Popup dialog appears and asks actor whether he wants to save unsaved changes.
    • 3a1a: User chooses to save unsaved changes and application saves edited presentation. Application shows dialog for opening Markdown file right after saving.
    • 3a1b: User chooses not to save any changes. Changes are discarded and application Application shows dialog for opening Markdown file.
    • 3a1c: User chooses to cancel import process - dialog is closed, nothing happens.

• 6a: Error occurs during the import process.
  • 6a1: Error message appears with "Ok" button.
  • 6a2: After reading error message, actor press "Ok" button.
  • 6a3: Actor sent back to start screen.