about Windows window Refresh principle

Windows Window Update uses the so-called "redraw" (REDRAW) mechanism, and the window content is updated after the content is updated to send a message that causes the window to redraw. 
But some of the changes do not inform the window itself, such as the Web page on the server, it generally does not know which window is browsing itself, so also
No notice. To cope with this situation, the General browser or window that displays the content provides "refresh" to re-browse the data to force the update of the window contents. I'm
feel that, in a sense, this mechanism is also a major flaw in the Windows operating system .  

Monitor Bandwidth
The wide bandwidth can be processed more frequently and the image quality is naturally better. Professional display and general application of the display of its bandwidth gap
Is huge, the higher the bandwidth, the higher the price of the display, which is why some small-brand monitors are reluctant to mark the bandwidth standard.
In general, our simple formula for acceptable bandwidth is:
Acceptable bandwidth = Horizontal Resolution x vertical resolution X Max Refresh frequency X1.5. For example, a monitor that supports 800x600x85hz
, then its bandwidth is 800x600x85hzx1.5=61.2mhz;
A monitor that supports 1024x768x85hz, then its bandwidth is 1024x768x85hzx1.5=100.2mhz. While some high
The bandwidth of the leveling display is more than 300MHz.

 screen refresh rate
The speed at which the image is updated on the screen, that is, the number of times the image on the screen appears per second, in Hertz (Hz). The higher the refresh rate
, the smaller the screen flashes, the higher the stability, in other words, the better the protection of vision. Ordinary eyes, not easy to detect
75Hz above the refresh frequency to bring a sense of flicker, it is best to adjust your display card refresh frequency above 75Hz. It is important to note that not all
Some display cards can be up to 70Hz above the maximum resolution of the refresh rate (this performance depends on the speed of the RAMDAC on the display card), and
And the monitor may not be able to meet the requirements because of insufficient bandwidth. 

about Windows window Refresh principle