For one thing, on most modern systems there isn’t a framebuffer, there’s only a simulation of one created by GPU compositing.
For another, security. Your application doesn’t get to scrape other applications’ windows and doesn’t get to put stuff in them, and they don’t get to do that to yours, unless properly entitled & signed. You can self-sign for development but for distribution that ensures malware can be blocked by having its signature revoked.
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For one thing, on most modern systems there isn’t a framebuffer, there’s only a simulation of one created by GPU compositing.
For another, security. Your application doesn’t get to scrape other applications’ windows and doesn’t get to put stuff in them, and they don’t get to do that to yours, unless properly entitled & signed. You can self-sign for development but for distribution that ensures malware can be blocked by having its signature revoked.