Would it cause browsers to change the way they open? First Safari started opening in half the size. Then my other browser. I haven’t installed any anti-virus or malware pgms on my 2017 Macbook, nor installed Mojave. Anyone like Mojave? I like to wait til initial bugs are fixed.
BTW, Sword, Apple has it right now to replace my whole keypad due to sticky key problem which some recent laptops develop. They are doing it for free not only because I bought AppleCare but also because they are saying it is their fault. So if anyone develops keys that don’t work or repeat, look this up.
It shouldn’t. The goal of any malware is to be invisible. For example one of my client offices had two employees click OK on a Adobe Acrobat Reader update pop up ad on their Windows 7 computers on January 7. . . What they got was a Trojan that turned off their anti-malware protection. One just got a browser hijacker that looked exactly like Google except it was spelled "G00gle" on screen but linked to an ad server webpage instead of Google. The other computer got the hijacker plus 1,979 other malware as well. . . and slowed down to a crawl. Both could no longer see the Windows 10 computer or the network printer they shared the office network with. . . But the search screens still basically looked like Google search screens. The URL address did not.
Safari and other Apple Mac browsers remember the screen size you last used. So if the malware opened a pop-under screen that was smaller than your normal browsing screen and it was active, often the case with persisten malware, then when you quit the browser without making your current screen active, it’s likely it will open in the remembered, smaller active window size.
Once you have your keyboard replaced, buy a keyboard skin. They’re about $12 and keep everything out. Don’t try to use the little stickies they provide, get some Scotch double sided tape and use that on several keys to keep it adhered to the keyboard and it will keep dust and other crud out.