KOReader has a built-in virtual keyboard.
Virtual keyboard automatically pops up with the input dialog.
Tap the screen outside of the input field to hide the keyboard.
Tap the input field to show the keyboard.
Keyboard language layouts
Language layouts can be added in the main menu Settings - Device - Keyboard layout.
The Earth icon switches between the added language layouts.
Holding the Earth icon allows to choose from language layouts which you selected in the Settings, or from any other available language layout directly (by tapping the second Earth icon in the popup).
Keyboard layers
Shift switches to the upper case layer.
After typing the first capital letter the keyboard will not turn off the Shift mode, so you need to do that manually.
Sym switches to the symbols / digits layer. The 1/2 or 2/2 icon shows on which symbol layer you are currently on.
Äéß switches to the upper unicode table layer.
Keyboard holds and swipes
More characters and actions can be invoked with buttons holds and swipes.
To input an additional character from a small popup keyboard, swipe to it from the initial button or just tap it.
Special actions are invoked with the hold of the following buttons:
Backspace - deletes all characters from the cursor to the beginning of the line;
← - moves the cursor to the beginning of the line;
→ - moves the cursor to the end of the line.