1. Gray out 'OK' button in 'SHA256 Checksum' dialog if no checksum text presents in dialog text box. I think availability of 'OK' button with empty checksum text field is redundant - user can press 'Cancel' button if he changed his mind to enter (or he doesn't know) checksum. 2. Do not show 'ISO is invalid: Requires an SHA256 checksum' pop-up window after pressing 'Cancel' button in 'SHA256 Checksum' dialog. Pressing 'Cancel' button suggests that user wants to cancel iso verification - informing him that iso is invalid is invalid). Instead 'Running ISO verification, please wait...' text can be replaced with 'ISO verification canceled' with out any warnings.