--Issue Overview--

There are two related problems that happen in both vector & bitmap layers.

First the stroke latency: basically every drawn stroke lags behind the cursor or pointer.
Second, the Stroke interpolation: Speed is a factor that modifies how the lines are interpolated, thus giving it enough precision to mimic the stroke that was input from a graphic tablet.

Both problems become altered when the Pencil2D window layout, and thus the canvas size are reduced as shown in the video demo.

It's important to say that in previous version 0.5.4b both Stroke Latency & Stroke Interpolation were present but it was to such a minor degree that they were barely noticeable for the regular user.

--Video Demo--
https://www.youtube.com/watch?v=9pTepQSgLCQ&feature=youtu.be

--Steps to reproduce--

Stroke Latency & Stroke Interpolation

1. Open Pencil2D
2. Select a drawing tool (i.e Pencil)
3. Select either a Vector or a Bitmap Layer
4. Try to draw as "fast" as a normal stroke with pencil and paper would feel like
5. Notice both the stroke lagging behind the cursor and the poor interpolation
6. Reduce the Pencil2D Window Layout to Half it's size (make it to occupy half the screen)
7. Try the same kind of strokes as in step 5.
8. Notice the reduced latency and interpolation problems.

--Expected Results--
Stroke Accuracy ( Latency & Interpolation ) should be independent of:

• The Window layout size
• The Canvas Size
• The Document / Camera resolution

Purely from a "User Experience" standpoint the stroke drawing interpolation method should not be apparent to the user, or it can throw off their drawing perception with the program and limit their freedom while creating artwork.

--System Information--
Pencil2D Nightly Build 15 Jan 2016 / Nightly Build 16 Feb 2016 (Run & built with Qt Creator 3.4.2 based on Qt 5.5.0)
Windows 7 64bits SP1
ATI Radeon HD 6770 1GB
AMD Phenom II X4 965 BE 3.4 GHZ
4 GB RAM