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UI
Pixel
Tango
warning, Dialog
Black
32x32
Mixed
Led Icons
stop, Alert, warning
Chocolate
16x16
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Twotiny
Alert, File, exclamation
Lavender
14x18
notification, Alert, warning
SaddleBrown
4x15
Computer & hardware
ASP.NET icons
Attention, warning
Olive
warning, Attention
OrangeRed
Desktop apps
Circular
Alert, exclamation, warning
Gold
Fugue Icons
cross, Circle, Error
DarkSlateGray
Mini
Alert, warning
Khaki