Input textbox accepts enough input to freeze the program

[beercanchicken]

Description

I mistakenly pasted about 1 mb of text from the clipboard into a conversation and Element. Initially I tried to delete it, but deletion caused the program to freeze. Although the UI was frozen (I let it sit for about 2 minutes), Element had saved it as a draft and performed a normal quit. The text was still present in the input box the next load and therefore the room hasn't been usable because the bug becomes a loop.

Steps to reproduce

• Gather large amount of text (1.0 mb / 14223 lines / 1,063,246 characters in my case)
• Paste it into text box
• Select all, delete text (UI should freeze)
• Quit application
• Restart application
• See large amount of text in textbox saved as draft
• Select all, delete text (UI should freeze)
• Quit application
• Restart application
• See large amount of text in textbox saved as draft
• Select all, delete text (UI should freeze)
• Quit application
• Restart application
• See large amount of text in textbox saved as draft
• etc.

Possible solution(s)

• Truncate text at an arbitrary amount that is high enough to not be noticed, but low enough to keep performance in check.
• Evaluate for any unnecessary text processing during delete text action (delete keypress, delete event)